Unless this is an older picture, I'm gonna say doctors. I'll also assume that it is because the transmission frequency of a cell phone causes problems inside hospitals. These are also smaller and more compact than a cell phone... and if you drop one, who cares?
I'll also hazard a guess that its possible that these might not be actual pagers, but internal hospital pagers that don't work in the outside world. Hence the reason they have so many... they grabbed a bunch at the check in station as a joke.
I'm sure that's a joke anyway, those are two way texting pagers. No need for multiple pagers, just send a message who it is & what they need.
I'll also hazard a guess that its possible that these might not be actual pagers, but internal hospital pagers that don't work in the outside world. Hence the reason they have so many... they grabbed a bunch at the check in station as a joke.