You can't open my chrome browser without unlocking my machine. You can't unlock my machine without 2fa. I don't walk away from my machine without locking it. So, technically, there is a master password if you lock your machine.
Nb:not saying it is cool to be doing what they're doing.
The data on your disk isn't encrypted with two factor authentication though. If someone were to remove your disk drive and crack your password, that second factor doesn't really slow them down.
Actually, OSX offers FileVault which is on. The 2fa is a password and yubikey with static pass, so the whole pass is ~40 chars. FileVault uses AES-128 which should, combined with 40 char pass, at the least, slow them down (depending on who it is of course ;)
Nb:not saying it is cool to be doing what they're doing.