The way contracts are worded, time working on on-call is work-time. Kinda obvious if you write it like that. As such, bad on-call weeks easily cut into the normal duties of the employee. This means team leads have an incentive to reduce time wasted on on-call.
You have mandatory rest-times. If an on-call activity takes an hour or so to fix, the person is suddenly not allowed to work for 10 hours due to these rest-time and maximum work time laws. Suddenly, "some little fixing at night" means the person isn't allowed to work the whole morning.
With a few rules like that, pages become really painful to the company. When a bad application kept pinging on-call every night for a few days, the entire normal work ground to a halt with people being unavailable, other team members dropping project work from sprints to pick up daily business slack. Some product managers got really pissed off and things in that product improved - I'm kinda curious what happened behind closed doors there. .