I believe as a running gag, in some of the Grand Theft Auto games, whatever vehicle you are driving in will appear significantly more often. Not sure if this is still the case, but I always found it amusing, since yeah, I also noticed this effect in real life (even if it's just fallacious.)

I noticed that as well but for whatever reason I just assumed that it was so that

1) You wouldn’t be seeing so many other cool cars and thus be tempted to switch cars all the time as that would distract you from driving where you were going.

2) If you wrecked your vehicle it would be easier to get a new one of the exact same kind.

But I think your explanation makes a lot of sense. They embedded a lot of humor in those games.

It is also conceivable that they initially did it as a joke and then once they had implemented and play tested it they discovered the benefits mentioned above, and made the case stronger for keeping it that way. We may never know :)

I have read, though I'm struggling to find an original source, that it was due to memory constraints - it was easier to spawn a vehicle if it was already loaded than to keep paging between them.

That sounds like it is probably true. I have never heard any official confirmation that it was a gag, so I think this explanation must be the correct one.