Blasters don't run out of ammo.
Or gunpowder weapons were never invented in the starwars universe.
Or if they were invented it would be very hard to find the weapons, and ammo, and reloading would probably get you killed by other weapons that don't need it.
They exist, but are very rare. Jix used slug throwers on people who used rayshields. He carried one blaster and one slug thrower. Read Shadow Stalker.