Ads for colleges in the subway aren’t meant for you, though. You probably already have a college degree and are well-educated. Those subway ads are for people who aren’t as well-educated, never went to college and are trying to fit it in between working, and wouldn’t get into a top-tier college.

Exactly. The top-tier college in the city probably has a subway stop with its name in it. Those ads are aimed at someone who doesn't have a college degree and/or has been contemplating doing something positive about their career. So part-time/night college, nursing school, etc. ads are there to nudge them and to suggest a specific option for them to consider.

I believe the thought was that if they were so prestigious they would not need to advertise at all. I have never felt this way about Universities, but I certainly have for defense attorneys.

Of course they advertise. They just do it in subtle ways called PR.

I used to do marketing for HE, and that always used to be the case - however the explosion in intakes has really skewed the market. Increase in tuition fees has also turned it into more of a transaction, so it's now less about selective prestige, and more about outcomes (which lends itself more to outward marketing than traditional reserved means).