Those "suckers" are easy to contract out to, and a lot of colo providers provide managed services or "remote hands" themselves as well.
In practice, when I was responsible for racks in two separate data centres, I spent 3-4 days a year in the data centres (combined); everything else was handled easily via tickets or remotely. Overall I've generally spent less time on devops with hardware in colo's than with cloud setups.
But specifically the amount of on-call work tends to be down to code quality and higher level architecture not whether you host in cloud or colo or rent managed servers - the "low level" problems become part of the noise floor very quickly in any system with reasonable failover.
In practice, when I was responsible for racks in two separate data centres, I spent 3-4 days a year in the data centres (combined); everything else was handled easily via tickets or remotely. Overall I've generally spent less time on devops with hardware in colo's than with cloud setups.
But specifically the amount of on-call work tends to be down to code quality and higher level architecture not whether you host in cloud or colo or rent managed servers - the "low level" problems become part of the noise floor very quickly in any system with reasonable failover.