If it was GM or Chrysler, I would also assume the stupid decision to glue a flat piece of metal to another flat piece of metal that people are going to stomp on was because glue is cheap.
This, unfortunately, is a Musk run company, so the real reason was likely hubris. Someone's over engineered solution getting axed for cost is the least likely reason. It's more likely that the man child in charge (or a hand picked manchildlett crony) thought welding / mechanical fasteners were beneath them and that the glue was actually a sufficient and elegant solution to maintain clean design or some other form over function reason.
Always has been. He's just trying to make his own gas station bathroom version of the extant MLM with his face all over it.