Actually a lot of legacy carriers put cadets in the right hand seat. British Airways does not have the position of Second Officer so all cadets go straight into the right hand seat of a jet. I have flown with many Captains who started at BA as a 180 hour cadet in the right hand seat of the 747 classic, DC10, 757, 767, A320. With most being under 20, can't really fault their safety record either.
You may not agree with the cadet scheme from a 'terms and conditions' point of view but please don't suggest for one moment that someone with such low hours is incapable of flying a heavy jet.