There are more or less permanent encampments along Boulder Creek right in the middle of town where overnight camping is technically illegal (which is the case anywhere in city limits actually). I volunteered for the annual creek cleanup that Rocky Mountain Anglers sponsors this year and when the cops were called about one major camp (complete with sofa's and recliners), they said "no, that portion of the creek is on CU property". When the CU police were called, they couldn't be bothered.
If there's no penalty, why would anyone expect these homeless to obey laws?