That's the problem, but there are no easy answers. Most leagues in Europe get a lot more TV/Sponsorship money than we do. We rely on gate money for most of our income. If we drop the prices, then we drop the quality of players we attract.
To watch the same players perform in England costs the same (or more). If there was an answer we'd probably have found it by now, but so far it's better financially for clubs to have 4,500 fans at 22 quid than 5,500 at 15 quid.
A longer term solution would be for the SPFL and SFA to do something, so we can rule that out.