90k people in one building?

And yeah, obviously companies have swipe cards/ids. I think that differs from name tags

Large companies do it primarily for security. I like to feel safe at work.

No name tag = Unsafe? Police state?

Lots of us work or have worked at technology companies. The badges open doors so there's an auditable log of who comes in and out, and strangers can't come in at all. They're not for people to read your name. There's virtually no data center worldwide where you don't have at least that amount of security -- PCIDSS says you can't process credit card payments on servers in facilities without auditable access control like that, for one.

I, for one, don't want some random person on the street to be able to walk into a Microsoft office with their laptop, and be able to plug into the same private network Windows Live ID servers run on. With 90k employees, it's not like anyone else would know if that person belonged there or not.

Keycard.