Why do people keep pretending that useful things have not been invented

For example, I keep seeing waiting staff in restaurants struggling to carry more than a couple of plates and IK want to shout ‘There is such a thing as a tray” but some unwritten convention decrees the tray to an ‘object non grata’.  Why?

I am sure you can think of other examples.

Learning from the failure of others can be hugely rewarding.  But so can learning from their successes, their innovations, their ‘wins’.

If we pretend that useful objects and devices do not exist, we are doomed to recreating the inefficiencies of the past … and we have enough in the present to concentrate our efforts on!