> Like through taxes on the sale of the property

That just encourages corporate ownership of property (unless you mitigate that), but overall I don’t know why we’d disincentivize moving closer to a new workplace or into a smaller home once it will do for you.

It also disincentivizes speculation, which is just a flurry of repeated transactions.

Spec can be loooooong term, even longer than natural person

Perfect is not the enemy of good.

In a lot of places, due to tax revolts there are now property tax caps which effectively prevent this from happening.

Then the people have spoken. They can speak again and differently if they like.

This typically goes to the higher level of government. Not the local one that manage and build that transit system.

Why should the transit system butt into the jurisdiction of the traditional government just because transit is built somewhere?

As a silly dystopia, imagine that a transit agency could grab revenue as you suggest it might. Then everything becomes a transit land grab.

No, taxes on the unimproved value of the land

Property taxes include that, generally.