The blasters used in the movie era are... Basically unstoppable? They're the pinnacle of weapon tech as far as mass arming is concerned.

AFAIK no source goes into this, but I've always interpreted the Star Wars universe as having basically invented every single thing that it's possible to invent in their universe. Technology gets better or worse generation to generation based on how unified society is and the proximity of the manufacturer to certain hyper-rare resources, ie the Empire was able to build the Death Star not because they invented a really big laser, but because they centralized enough military manufacturing in one place to actually be able to build it.

Anyway that's the only way I can think of to square the universe's technology being basically indistinguishable between the three trilogies and stuff like KOTOR.