There are a lot of people unable or unwilling to let management's poor planning and time mismanagement flow back up to the management people causing the problems. Or they are convinced that their extra effort will be rewarded somehow without management being forced into awareness of it by the pain of missed deadlines.

In my experience management will just continue to dump on people who will grind away at shit until it is done scheduled hours be damned. They end up becoming too valuable where they're at due to the perseverence, while not actually building or improving any skills. Where's the time for skilling up if you're always busy being the guy churning through the pile of shit no one else will do?

It's the myth that hard work is rewarded. It is, but generally only if it's hard work due to difficulty instead of due to the time cost alone.

They also take home their laptops most weekends to “catch up”, “don’t fall behind”, or “just in case any emergencies”.

Why???

Cause they're using the work issued laptop for home purposes.

I do this just so I can be aware of what's going on because it makes less work for me during work hours. It have silent notifications on for that app, so it doesn't interrupt what I'm doing. I pretty much only read the subject line unless it pertains to me personally. It really only takes a few seconds out of my day, but it makes it so I don't need to start earlier and I can review my emails before my scrum starts at 9 AM. I start working at like 8:50 AM to get logged into my VPN and everything, while some of my coworkers start at 8 AM to review all their emails before scrum.

Some people in my office have their work email synced to their phones

Sure, but configure it to turn off notifications outside work hours. Unless you're oncall, it's probably fine to handle the new emails during business hours.