To me it shows a lack of responsibility and a huge lack of respect for the local laws. I guess not everyone feels that way though.
fwiw, I take traffic flow very seriously. I will always move over if I notice someone driving close behind me.
That's not a US only phenomenon. For example, in the UK there is a - somewhat justified - suspicion that some speed[1] cameras have nothing to do with safety and everything to do with revenue raising.
[1] Ahem, sorry, I mean "safety" not "speed", obviously.
the US has a somewhat fraught history with traffic laws. by default, police are not really allowed to stop you for no reason and possibly search your vehicle/person. of course, this is very inconvenient for police, so over the years many traffic offenses have been created to remedy this. if a cop wants to (legally) pull over the most upstanding citizen in the country, all they have to do is follow them on the road for a mile and they'll have a reason.