Symptom of a deeper malaise
Any employer feeling the need to monitor their employees to such a degree is at best only papering over the cracks and not recognising a deeper problem. Most people are good and fair-minded, and show loyalty when treated as adults trusted to do their jobs. Treat people well, with flexibility and understanding of their circumstances, and they will respond well on those occasions when the employer needs a few extra hours at short notice. Treat people with mistrust and hold them to every minute of the day, especially when overworked and under-resourced, and many -- if not most over time -- will effectively end up working to rule and be less inclined to be creative and constructive.
Good managers will be able to identify any slackers taking advantage of trust and goodwill, not least because the slacker's colleagues will soon make it clear they are not willing to put up with parasitic behaviour. Poor managers, on the other hand, are more likely to micromanage and look to a bureaucratic and/or intrusive performance improvement process because deep down they know they don't have the ability to turn a bad situation around by providing good leadership and showing trust.
Well, that's my experience anyway.