Ops generally have someone in those sorts of on call scenarios. You don't ask everyone to have that availability, that's insane.

Exactly. Unless you're a startup, just have a rotation for people on call. Also, resolving these issues tends to go far more quickly when you have as few people as possible looking at the issue. Those calls where you have multiple engineers debugging are generally a waste of time for most people on the call. It gets even worse when management and product ownership are also on the call asking questions. Like please, for the love of god let me work and I'll get an RCA to you when we find and resolve the issue.