Kithzer
Vanity plate - most likely the bus is private.
Yes, the license plate was chosen by the owner of the bus, company or private, doesn't matter, who will be merely affiliated with Flixbus. It's not a problem, just quite distasteful if you ask me to spend 3500€ on this license plate. That's the price of a vanity in Bulgaria.
Kithzer
A father and son are driving, a father is teaching his son to drive, what's wrong with that?
I really hope you are not serious about this... We are looking at multiple violations here: Unrestrained child in the vehicle, distraction of the driver from driving, and the child is operating part of the controls...
If this was an empty parking lot or village road and they were in a car I'd obviously have nothing against it. But they are operating a
BUS, possibly with passengers, on a busy public highway. This is multiple levels of dangerous and careless.