Thanks for the warning. I had some driveway work done last Spring and left two carts out overnight on the street, and I got lucky, but your post is a good warning not to rely on luck. I like the Apple AirTag idea, and they only cost $29, or 4 for $99, but while that may help to catch a thief, avoiding theft in the first place would be a lot less hassle.
Here is a YouTube link to a video on how to replace the ignition switch on a Yamaha. I expect most carts would be similar.
https://www.youtube.com/watch?v=pn5pH7DWtWk
The next challenge would be to find an ignition switch that would have a more unique key, rather than simply switching it out with another OEM ignition.