Perhaps an examination of the Colorado's state constitution would reveal language similar to the Eighth Amendment of the US Constitution, thereby making the proposed imposition of such an excessive fine, well, "unconstitutional".....
That would be a defense except so many "unconstitutional" laws are legal by virtue of the need for revenue. I note that the council considers the fine to be a tool for plea bargaining. That's known by another name, extortion.
The problem with many local governments is that morons are elected to positions of power that they do not understand, my little city included. It's fun to be a council person. They want to be one forever. They need issues to run on. If there aren't any, they will make up some. Just collecting the trash, keeping the water clean and maintaining the streets are no longer considered as doing ones elected responsibility. Every council person, in every town in America, wants a law to name after themselves.
Boulder, like a lot of cities in America, needs to form an independent city charter committee and begin reigning these power hungry morons that wind up on city councils.