Yes it's normal, not right, but normal. It's what hospitality staff (and probably others) do every day to provide the service people demand.
It doesn't matter how many staff you have on, people don't want to wait, if not near immediate and perfect service then it's not good enough, even if you're with other customers, so they certainly don't want to wait because someone is on their break, even if there's a replacement available to cover, if they're with another customer then it's not good enough. So people don't have breaks in 8/10/12 hour shifts to try and avoid being shouted at for not being able to defy the laws of physics and split themselves in several pieces and serve everyone at once.
I tried to leave 4 times yesterday, already an hour over my shift, even with my coat on and half way out the door I was being asked to do things by customers because clearly I only exist to serve others.
That and not being able to predict the future as in know how many people you're going to get through the door on any given day to be able to put adequate staffing in place, you can guess certain times and days will be busy and staff to that, and you don't dare turn people away because if you've got empty tables to try and manage the situation on the staff you have, and tell someone you can't accommodate them it's simply because you're being awkward and stupid because you have a free table.
And people don't want to work in this environment, and they certainly don't want to invest themselves in it, especially when there's an attitude towards these jobs that they're 'beneath' others. So recruitment is hard.
So yeah it's normal in hospitality because that's what's expected by the general public.