There's different ways to look at it. Of note: The previous BSAR fee was set at 25 cents and has not changed since 1987.
I buy a fishing license + another 4-5 big game licenses annually. Definitely pay my share, but even then, we're talking, what? $7 annually to support S and R. I'm not sure there is a practical way to obtain funding from other user groups since there are no licenses involved with the exception of SWA permits. The state can't charge mtn bikers a licenses fee to ride on FS/BLM land. Unsure how you would develop a system when there is no existing systematic framework. Developing a system of collection would eat more into the budget that goes to S and R.
I don't conclude that there is enough there to complain about. The quality of of S and R throughout Colorado is impressively high. The volunteers that are into it are WAY into it, many of them having quite a bit of their own money wrapped up in participating in S and R + you get fire departments, county EMTS and even aircraft with extensive training in high angle rescue, avalanche rescue, swift water rescue etc. From what I've seen, I've been very impressed.