some of these musicians BUY A SEAT for the violin in order to protect it.
There has to be a reasonable solution. Imagine the isurance liability for loosing a million dollar violin.
There was a reasonable solution. Travellers would carry their delicate goods themselves, purchasing additional cargo space (a second seat) when necessary. If you want something done right, do it yourself.
Reasonability of course has no place in our PC game of treating all citizens like terrorists so as to not offend anyone.