As a Canadian that recently moved the US, the system here is utterly ridiculous and broken.
No argument here.
I never know when I should swipe vs insert the chip, I have never been asked for a pin, sometimes I have to sign and sometimes I don't (there doesn't seem to be a clear limit), and there's no tap-to-pay.
You can always ask. The monkey behind the counter probably knows. And most terminals I've seen have some sort of indication - for example, a light by both the swipe slot and the dip slot (or whatever you call them). If only the swipe light is lit, you swipe. If both lights are lit, you dip (assuming you have a chip card). Or the POS will say either "Please swipe card" or "Please swipe or insert card".
If you want to use a PIN in the US, you can always get a debit card. But otherwise, you will never be asked for a PIN on a credit card.
The no-signature rules vary by credit card issuer, merchant type, merchant implementation, and purchase amount. For certain types of purchases, certain types of merchants, or merchants who have not implemented it, you will always be asked for a signature. Otherwise, there is generally a $25 or $50 limit, with the higher one usually applied to grocery stores and big box retailers.
Tap-to-pay support is still quite limited, that's true. But one of the nice things about the Chip and Signature transition is that all these merchants are having to buy new POS terminals, most of which include tap-to-pay. It just will take a while for them to update their software and turn the feature on - plus some of them are still hoping that if they don't let you use Apple Pay, et. al., that they can force you into their competitor, CurrentC. (I don't actually know the current status of it, but it seems... questionable at best. But all the same, the stores that supported it are at least a year or two behind everybody else in implementing tap-to-pay – and everybody else is a year or two behind the wide release of phones that support it.)