Am I mistaken, or do presidents no longer have veto power? And are presidents no longer able to influence legislation, say, like Biden did with the Infrastructure bill?

They do still have veto power, but it's exceedingly rare in today's age of deep partisan division, slim Senate majorities, and robust use of the filibuster. And they can influence legislation, but the import of that pales in comparison to their role in overseeing the Executive. Again, in an age of slim Senate majorities and partisan division, the shape of any legislation is going to be determined mostly by the preferences of the marginal Senators whose votes are needed, and not so much the preferences of the President.

But sure, you can go ahead and vote for the guy who says he'll get the trains to run on time (or build the wall and get Mexico to pay for it, or secure the border with EOs) even though he failed to do so when he held the office the first time around.

Oh, I'm not voting for Trump - but I think you underestimate how much your typical Republican preferred the Trump Administration to the Biden one. Just because, again, Trump's Administration was mostly a bog-standard Republican one for 80-90% of the stuff. The agencies mostly issued interpretations consistent with how conservatives view policy should be, mostly pursued projects consistent with what conservatives like (more highways, less transit, not as much trying to cut everyone's carbon emissions), and generally didn't try to "bend the arc of history" toward progressive goals.

Sorry, albaby1, but this ain't no normal campaign.

That's what Michael Anton said, too.