Are these things going to be clogging up bike lanes
You must not be from the US. Bike lanes here are empty, mostly treated as extra shoulder for cars. I'm not concerned about this one bit.
making biking more dangerous for people that aren't working for Amazon
No, I feel confident that fewer motorized vehicles does not mean more danger for cyclists.
Are they going to have their "drivers" risking their lives on the roads with real cars? Are they going to be out there peddling hundreds of pounds of packages for 8 hour shifts in 90 degree weather?
Except for the peddaling that sounds suspiciously similar to current conditions. That needs to be addressed too, but I don't think vehicle type alone is sufficient.
