Any idea why Tesla went against that to a shatter proof glass?
Because Elon Musk is a manchild who thought it was cool and forced his engineers to entertain his idea? The entire design of the Cybertruck just screams "someone high up had a shitty idea and told engineering they had a month to figure out how to make it real without any regard for rules or regulations".
Justices need to die or retire in order for there to be a vacancy for a President to appoint a new Justice to. There was a vacancy at the start of Trump's term due to a death during Obama's that the Republicans refused to confirm an appointment for, and then there was a retirement (Kennedy) and death (RBG) during his term as well.