Your perception, nothing more.
You're exactly right, from your individual perspective. But conservatives as a whole, especially lawmakers reject reform. Conservative lawmakers are active over status-quot issues, not change. The only US conservative lawmaker currently in the mainstream news is the house rep that wishes to strengthen fines and incarceration for mj violations. While he's not the end of the issue, none of his fellow conservative lawmakers disagree enough to advocate mj reform. Unless you're willing to count Ron Paul. IMO he's a libertarian, regardless of his party affiliation.