They have no right to do that, at ALL. Legally, an employer can give you zero paid vacation, but if they require you to be reachable during YOUR weekend, it's their f---ing problem that they can't structure the team to have no fallbacks. In the least, have a rotation plan.
Legally they can do whatever they want - you're salaried, so it's not "your" weekend. It's a red flag and you should definitely start job hunting, but I'm not aware of anything that stops them from imposing this requirement.
Is this like an American thing? You don't own people just because you pay them a salary.
In UK you cannot force someone to work overtime more than 48 hours, averaged over 17 weeks. If they require you to be available over weekend, they would probably have to count it towards overtime.
I would find it unconscionable to be available 24/7, how are you meant to go along your daily life?
What's the purpose of that anyway, you are not working as a paramedic??
