Sometimes it does. I've seen people go from the business side to the informatics side. I've seen nurses go from that side to the informatics side
Rarely does it happen usually the person ends up taking a cert or some other education to make that move. These major companies that you recommend ,often teams are split by buildings sometimes even campuses so even interacting with other teams is rare. HR is also extremely slow with loads of red tape at these companies which again makes this type of move very hard because there would probably be 10s of people that would need to sign off on it.
I used to work as a contractor at a faang company for 2 years along with many other contractors and hardly anyone was able to successfully apply for a position and get it as a full time employe. There where many contractors including me who were as knowledgeable as the fte's but still had no luck making that move. Contractors did about 60% of the same job fte's did but yet very few had success applying let alone getting a full time position.
Companies for whatever reasons hardly let people make these moves same way companies already expect employees to have experience. It's easier to make these type of moves at startups where there is less red tape.