If the organization of the effort is a crime, the group insurance scheme can be easily changed into individualized betting scheme. I'll bet $15 on not being caught this month on 8:1 odds. If I am caught, I get $120 to pay the fine, if I am not caught, my $15 will be lost. Or you could simply self-insure like I did. Problem solved. Now it is not organized crime anymore :)
The whole problem is that there is a very easy formula: fare - fine * chance of being caught
If this formula is positive, you pay too much in fare. But the cost of the checks to to catch fare dodgers ultimately increases the fare too much. Increasing the fine beyond a certain limit lowers the amount actually collected, because people won't be able to pay the fine, which clearly would need to be 120/15 * 180 or $1440, which is too high for anyone to pay. It is a problem that most of the public transits face and it is not easy to solve.
A lot of cities solve it by sharply reducing the fare for students, because they are the most likely demographic to cheat and to have highly reduced monthly/yearly passes. And they simply expect that for older people (>30) it is simply too embarrassing to be publicly caught, possibly in front of colleagues and business partners and the cost of the monthly pass is worth it to avoid the embarrassment.