Is it bad to start and stop engine without driving?

If this is all that happens for months on end without any real driving, then yes, it would not be good for the car. However, if it is getting taken out and driven say once per week, there's no real issue. There is some wear/tear for starting a cold engine, but really it's negligible. The real problem is not running it until the vehicle is completely warmed up (engine/transmission/differentials) at least once in a while. That's only because seals dry out and the battery never really gets charged completely. Other than that, no, you aren't going to see any appreciable wear from what they are doing.

Unless the car is given a long drive or there is a battery charger connected, this will result in a flat battery fairly soon.

We used to say a journey of 7 miles at reasonable speed was needed to put back into the battery what was taken out by starting the car, and more in winter.

This “estimate” was given to customers who used their cars as shopping trolleys once per week for a total round trip of 5 miles, which led to them breaking down. Once we got them to add a weekly long trip there was not an issue.

This would come to light after a thorough check of the starting and charging system.

I don't know if your car is Manual or not but if it is, I would consider just put the handbreak off and moving the car without turning it on and then putting the handbrake on again and that's it.