Why doesn't Equestria have police forces?

There’s only one jail and it is in Appleloosa. I bet ponies who get arrested must be transported in a wagon to Appleloosa. That takes time, so most ponies just forget it. Maybe there’s some sort of “house arrest” magic spell ponies must go under
 
also, I agree. Royal Guards are also police. using their magic makes it easier to cuff/restrain violent criminals. perhaps there’s an underground secret dungeon. we know dungeons exist

@Background Pony #A60F
 
One jail we ever saw. there are probably more.

@Mildgyth  
Hopefully there’s plenty. I imagine drunk flying pegasi end up in jail frequently

There was a cop in The Gift of the Maud Pie.

@Chrys  
Yes I love that scene. Pinkie almost got herself arrested in that one!  

 
Oh yeah, resisting arrest only gets you in more trouble  

Manehattan has police officers. But they don’t need police force for the entire country because police are corrupt and abuse power. Heck the Royal Guard are useless as is.

Maybe, we just don’t see them?

@Zaknel  
Secretly ponies get arrested all the time. we just never get to see them
 
 
@Background Pony #39EE  
I think that’s reasonable. Manehattan is probably the most populated anyway. Is that why Rainbow Dash never got arrested for destroying the weather factory?

@DragonBoi471  
There are cops in some places (like Manehattan and Appleoosa). It’s just Ponyville which seems strangely devoid of constabulary, although I think you are being a bit unfair expecting what would realistically probably be just a few part-time constables to deal with giant dragons and supervillans with powerful dark magic.