74 Pontiac and a brand new 79 Corvette " unfixable I find that hard to swallow.
A view point from middle class
Besides those was the ugly years that nobody consider classic or muscle anyway. about 1971 and maybe 72 was the last of the classic muscle cars. For nerds they probably don't even know what look like let along know what year. That's why you rarely see 73 up models collectable (few specialty maybe like Grand Nationals) .
IMO For us that use to work on cars back then probably the last few years of fix-it yourself cars.
For those that can't find spark plug they all were unfixable.
As far as your holly grail lux nerd models from over seas. 100 bucks for spark plug or wire (notice I said ONE) way over the top IMO or 800 plus routine services. Most new owners don't keep cars long enough for spark plug change let along doing the routine Maintenance work required. So they never see the real cost. It's the second hand owner's that want the status at half the cost that find that out.
Foreign manufactures and probably most manufactures require factory trained dealership workers to do routine maintenance or you warranty will probably Voided if you read the fine print. Most Any make of car made now days will last three years doing nothing to them that's imported to USA. GM is no better or worse than Toyota, Honda, Mercedes, BMW, or your high priced rice burners ect.. But, don't hold the nerd cult following.
Visit Junk yard and you will lots of 10 year old foreign along with all the other brands.