Because, like most medical issues, it is far more complicated than bean counting.
First of all, that vaccinated person has to be a "breakthrough" case, and that number is very low
Then, because the vaccinated person has antibodies to the virus, it is certainly possible, if not likely, that any viral particles transferred are much less likely to infect anyone.
Then, even if active virus is transferred, it has to be a susceptible host---ie: the unvaccinated
So the chances are quite low---I went through all the math on another similar thread.

Agree 100%. Follow the money sheeple.

I wanted to punch the face of the smug Alabama Governor. For 18 months she, most Republicans, and Fox would not do anything about the virus and reticuled those who did — and now that 95% of the deaths are the unvaccinated she shames her ignorant base into getting the vax!? What a hypocrite. And a murderer. Let ‘em die long, lingering deaths.

Not in Free Florida

Not looking to argue for the sake or being disagreeable, but I fail to follow your thinking. A vaccinated person with a Delta Variant viral load is a breakthrough case. It really has nothing to do with what we are discussing. The comment made, was that a vaccinated person has a much lower chance of catching the delta variant from a vaccinated person with the same viral load as an unvaccinated person.
To your second point, are you suggesting a vaccinated person with a positive viral load of delta variant transmits some type of immunity along with the virus to another individual? That is the only way I can see what you are saying being logical. IMO, a vaccinated person with a positive viral load of Delta Variant covid is as likely to transmit the disease to person x as an unvaccinated person with the same viral load.
Your third point I disagree with as well. The chances of a vaccinated person getting the Delta variant of the virus may or may not be lower than a non vaccinated individual (I know they say the effects are less severe. Has it been studied yet if the vaccine prevents the transmittal of the Delta Variant?). I hope you stay healthy and happy.

Ahh from Chicago, now it makes sense.

I am vaccinated and refuse to mask up again. The mask has little benefit anyway.

No, I believe it was living.

But, but, but----how do you really feel????

I went through the numbers on a related thread, so I agree, however, we may not get that choice

Well, again it just doesn't work that way. If I find my previous explanation on another thread I will repost it here so you can understand what I'm saying. But basically, you first have to find a breakthrough case to have a viral load. The last CDC number was 0.01% of 180 million vaccinated people. This is probably much higher but who knows. Then, in your scenario you have to assume that the antibodies raised by the vaccine haven't damaged the virus enough to render it inactive BEFORE it even gets to another person. Then, that person has to be susceptible, which again according to CDC numbers is essentially the unvaccinated and 0.01% of the vaccinated.

So, you might be right, IF, we only discuss vaccinated people with a viral load that is just as contagious despite being in the presence of antibody in the vaccinated person transmitting COVID to an unvaccinated person. Not a real common scenario since the number of breakthrough cases is low (as of today, who knows what tomorrow brings)

If vaccines work then why are masks mandated? If vaccines don't work, then why are vaccines mandated?

Many of our schools have become prisons and our children biological hazards. Why?

Really, now we are blaming the immigrants unvaccinated ! Lets start where it belongs... how about OUR OWN UNVACCINATED LEGALS that refuse to be a part of the solution instead of THE PROBLEM.

A story about life in the ‘burbs. . .
 

I am with you.

The psychology of those who cling to dysinformation would be fascinating if the rest of us did not have to be among those walking incubators. (Yes, I use ‘dys’ as the prefix rather than ‘mis’ because it is the more appropriate prefix.)

In one of my social groups, there is a woman who told me over a year ago that she knew the virus was being overstated because she had heard her. . .uh. . . how should I say this. ..uh, cult-leader (?) speak about it on television and that she “loved” him. Yep. She said she “loved” him on his previous television show, too.

Anyway, later on, she was hospitalized for Covid.

I saw her recently, for the first time in a long time. She had always been one of those women who is very put-together, accessorized, dressed to the nines, and her hair was professionally colored, beautifully. But now she has aged far more than a year should show, her hair is brittle and fragile, and her hairstylist told her she is seeing that hair-effect with those who have had a bad bout with Covid. Her colorist actually suggested she stop coloring her hair. (gasp)

She also told me that she is having a hard time getting past feeling generally not-so-good.

AND YET — she launched in to a thing about “freedom” — spouting all those canned phrases that have been programmed into her.

I wanted to say, “Well, you look like hell and you once looked damned good and you just blamed Covid and now you still cannot connect the dots??”

But I did not say that. I just privately decided to avoid her socially.

Damn. She has caused me to turn into one of those mean girls from high school. (sigh)

Boomer

By 'legals' do you mean American citizens?