One is contributed to by the community. The other, not so much

That hardly sounds as the main reason for this

I bet the difference is teams has to play ball deeply with Microsofts famously hideous login systems whereas code is a standalone product (Visual Studio is also good, everywhere except the bit where you have to log in to license it).

I've coded up Microsoft's collection of login systems. They are actually not that extraordinarily difficult to use.

Whatever is happening in Teams it's its own special sauce of terrible, combined with a complete reluctance to shoot Teams in the head and start again.