I sat down this morning to write an article about food safety and handling issues with NA beer, but then I found Good Beer Hunting’s article, which does a great job of outlining the issues. So here’s a quick high level summary about the issues involved, but you should really go read their article for more detail.
TLDR: Not all beer is pasteurized. Many (most?) craft breweries skip this step because pasteurization equipment is expensive. The alcohol and hops in regular beer help protect drinkers from most hazards (an infection might lead to sour off-flavors but things like listeria are less likely).
NA brands have struggled with hit-or-miss quality controls (unintended funky, sour flavors, burst packages from accidental secondary fermentation) and safety issues (Guinness’ recall of NA beer due to unsafe biological contamination). Some brewers insist on tunnel pasteurization (this takes filled bottles and cans through a small tunnel where they’re sprayed with hot water and is a good way to pasteurize everything (from the liquid to the container itself) in one go), but this is expensive equipment that small brewers can’t afford. Other brewers see this as a gatekeeping exercise that supports larger breweries, and they insist they have their own, often proprietary methods of keeping their product stable and safe. The GBH article doesn’t go into this, but there’s also some controversy over whether NA beer can be properly and safely served in a draft system or not.
“Everybody’s Got One — Opinions Clash as Non-Alc Makers Debate Quality Control Methods” written by Kate Bernot for Good Beer Hunting‘s Sightlines.