Since banning overselling would increase ticket prices, there will inevitably be some passengers who would suffer as a result. Statistically we'd find that some passengers can no longer afford to go on holiday, etc. These passengers surely want a cheaper ticket so they have _some_ opportunity still.

Instead, I think the most reasonable solution is to allow oversell but enforce adequate compensation by statute, which is what we have today in many places.

The difficulty is in deciding what constitutes adequate compensation. Too much and we'll be back to the "no oversell but inefficient and therefore high ticket price" situation. Too little and traveling would be a mandatory gamble that passengers might be wiped out (eg. a weekend away ruined with no compensation to go again another time, etc). A balance is needed. Banning overselling completely however is I think too far in the wrong direction.