It's silly but not surprising. This is one of the consequences of Boulder's decisions years ago to restrict growth.
Here's what I mean: back in (I believe) the 1970's, the city of Boulder saw what was happening in nearby cities including Denver, where suburban sprawl was spreading the cities out for miles and miles. The Boulder folks decided they didn't like that so IIRC they either purchased land surrounding Boulder, or got an easement on that land and prevented it from being developed which gives Boulder a nice little "green belt" all around.
Of course, anyone who can add 2+2 could have predicted what happened next: Boulder's booming economy started adding jobs - but since they couldn't expand the city (due to the green belt) and it was tough to build more housing units (due to restrictive zoning laws), that meant that several very predictable things occurred: Housing prices in Boulder itself skyrocketed (increased demand + limited supply), parking and public transportation became a nightmare, AND, the nearby Suburbs like Broomfield, Lafayette, Louisville, Superior and Longmont - all of which were outside Boulder's Green Belt - became the only places that people who worked in Boulder could afford to live.
In essence, Boulder didn't
prevent urban sprawl - they simply
exported their urban sprawl to nearby (less affluent) cities.
It's kind of like the way people who live in LA and drive electric cars aren't "non-polluting", they're just exporting their pollution to the rural areas where the power plants (that generate the electricity for their cars) are located.
Anyway, the lefty-ness of Lafayette, Louisville, Superior, Longmont, etc, is a result of the fact that those places have become bedroom communities for Boulder - people who work or go to school in Boulder but can't afford to live there. So it shouldn't surprise anyone that they keep trying to turn their little suburbs into mini-me Boulders.
