Perhaps I've been lucky to work at places where work did truly end at 5pm, about 90% of workdays (of course if the servers are on fire, or a customer can't log in, that necessitates after-hours work, but once it's done, it's done). It's a work culture thing, and instant communication channels don't necessarily lead to everyone being on-call 24/7. I'm sure that existed pre-internet also ("Boss called, I need to go back into the office and finish some paperwork...")