It's lazy parenting rather than interacting with your child, but I can totally understand making an exception for long waits like A&E or on a long flight. In those circumstances though, everyone is in a stressful and trying situation, so you're still awful if you have the volume on or don't give them ear phones to listen with.
Parents who let their kids run around are lazy too though. Yes, it's hard work to keep your child entertained in a way that doesn't annoy others when waiting for appointments or other things. That's parenting though. Read books, help them draw or colour, walk around with them looking at posters on the wall and talk about things. When you need a break, then give them a quiet screen for a bit sure, we have that now, but don't inflict it on everyone else.