The thing is a tad more complicated since the lore is a bit loose here. They say blaster rifles are for military use mostly~and well I would believe that if the movies hadn't showed us otherwise! Now here we can either assume that some rim world like Tatooine wouldn't concern itself with that but even if doubt that! I bet there are other Planets which also does the same way as Tatooine! So now I think there are actually blaster rifles which are downgraded for the civilian use! They mostly have nothing more than a higher stun setting! Which could also be upgraded to kill someone. 

Anyone can achieve a simple blaster and the tiny ones are originally created for civilians and believe me, there are enough energy scanners so you just can't hider away your blasters everytime! On the other hand a slugthrower pistol doesn't have any energy signals! 

I mean a farmer blaster rifle can kill those ugly desert rats....Same can a air rifle...But a human is another league! And a bb-gun will not get confiscated at the airport....A huge AK47 will! 

And raiders are only a problem in the outer rims....and they tend to give zero ducks anyways! Well until someone of us decides to show them a little law and order! 
Most bounties are on the outer rims...which isn't surprising at all xD