Ironically enough, Conservative interests made it a whole lot harder to amend the CO constitution in the last election-
http://www.denverpost.com/2016/08/15/is-it-too-easy-to-get-initiatives-on-colorados-ballot/
It's about protecting oil & gas interests but also has unintended consequences wrt A64 in particular.
As Miles has pointed out there's been some noise in the legislature about trying to impose more restrictive limits state wide but it bogged down, likely because it would be immediately challenged in court. Municipal restrictions wrt A64 have some cover under CO home rule provisions but even that really is shaky. Hell- even provisions against outdoor growing are on shaky ground because the definition of a locked enclosed space out of public view is vague.
Makes ya wonder if there still happens to exist an individual with an un-abbreviated grasp of the English language who could craft things with explicitness, lucidity and precision.
Or if they're making things vague on purpose....
...place your bets...
1.) the people crafting legislature can not read well.
2.) this shit is unclear voluntarily, after consideration, with full intent.