Where I live, the light rail isn't access controlled, so they send officers around randomly to verify that everyone on the train have a valid pass (and ticket those who don't). Nobody really complains about it or thinks it's invasive.

I don't see how this would be any different.

I am sure there are still people who manage to ride the rail for free. Not many, but there are. And that's ok, some low-level abuse is perfectly tolerable as long as it's low-level.

Same here, and for the metro as well.

That being said, IMHO it's better to tolerate a moderate amount of abuse than going over the wall with enforcement.