[toast0]

As an employee, I've typically needed to show up in person, but I've worked with contractors who never showed up in person. I've even been such a contractor at times.

Lots of commercial products use contractors and licensed code in the final product.

At least with most open source projects, a lot of the contribution process is in the open, so you could watch it you wanted to. As DonHopkins writes elsewhere, few people do, but it's possible. Not a lot of commercial projects offer that level of transparency into changes.