I don't know for sure if AK rifle barrels have chrome plated bores but if they do I believe it's a cost/time saving measure from having them heat treated to a higher hardness. They just wear longer then a none heat treated steel barrel and eliminating quenching will keep the barrel from warping requiring straightening. They can also use cheaper steel that "won't" get hard from quenching. And chrome plating can also peel so I wouldn't want a rifle with it. Just my two cents.
Seems To Me... ...that the far more worrisome issue is with barrel "rifling". This is why I opted for "inaccurate" AK rifles with chrome lining. They're not quite as accurate "at first" but they don't "lose accuracy" over a period of many decades due to rust.
If you ask 20 people why the Russians like chrome-lined bores, you'll get 20 different answers, and all 20 people will swear only their
answer is the correct one.
No matter where the discussion ends up...
I don't have to worry about my rifling rusting away. I have this crazy thing that I do...
It's really simple: I clean and maintain my firearms.
Amazing, I know. Whodathunkit?