They are for security, as part of a combination of things, including fire alarms and surveillance systems.

Imagine allowing just anyone to walk into your building.

I've worked on/with these systems, it's no small task to deliver what's contractually required with insurance companies and regulations. I've seen many times they've done their job - from preventing an employee's irate ex from entering building, to catching a car fire in the parking lot and notifying both the fire department and employees so they could move their cars, preventing the loss of hundreds of cars.

Of course an access control system could be (trivially) queried to see when people arrived/left. Most companies don't bother because there are far more effective/useful ways to address attendance issues.

Seems like TikTok has some issues if they're willing to do this. My guess is a significant number of managers aren't enforcing the attendance requirements because they don't deem them necessary. And who would know better than them?

Weird situation, for sure. Be interesting to see how it plays out.