Couldn't they get a rotating stand for the terminal, so in the case where it asks for a PIN from the customer, they could swivel the terminal to give the customer access long enough to enter the PIN?

I've certainly seen pre-EMV swiveling terminals at some US restaurants, where the same touchscreen the salesperson enters the order on then gets put into "customer onscreen signature mode", they spin it to face the customer, the customer signs with their finger on the screen, and then they swivel the terminal back to face the salesperson again.

And I seem to recall swiveling terminals for EMV somewhere outside the US too, though I can't remember where exactly...

... This is the kind of restaurant where I feel like going in with insufficient cash and only my Diners Club MC card. They'll try a little harder if I say that's the only card I have, and I don't have enough cash, and it's a good card. They can always, of course, write down the number and treat it like a take-out order with the card info taken over the phone. If enough people force such restaurants to confront the fact that their terminal technology is "not up to snuff", it'll get back to the restaurant managers and then back to the terminal makers. But if everybody just pulls out a different card, the restaurant manager is not even likely to hear (from the salesclerk you interacted with) that there was PIN card failure.