I didn't mean sterilized so literally, but if someone grows up being exposed to fewer potential pathogens or regional pathogens, then it can be a wakeup for an immune system, literally to be exposed to foods naturally carrying a higher microbial load.
The surface of meat certainly isn't sterile. Ideally, the muscle itself is if not contaminated by handling, processing, or the buyer. But, most people are now aware of the risks of raw meat and thoroughly cook most meat or what have you to reduce the microbial load. :D