I was just in a Walgreens near Boulder a few days ago and noticed that they were advertising for pharmacy assistants and didn't post their salary range, and also didn't list it even after I went to sign up online for the job. So I have to guess a lot of employers are disregarding the law. I was also disappointed when I found out there wasn't a particularly easy way to report the violation to the state. It could just be a webform that I fill out that takes 2 minutes, but there was so much overhead that I decided I didn't care enough to complete it.
I actually think they fixed the online version since the last time I checked - when I visited it 3 weeks ago, I remember the site staying on the "walgreens.jobs" domain for the entire visit - now it redirects to jobs.walgreens.com. I wonder if they were using an old poster from before the law came into effect, and maybe even the listings/website were old before the migration to jobs.walgreens.com - now they do include a link to the pay information, but I love how they make you copy and paste a URL instead of just directly including the info, or even making it a hyperlink.