I think a large part of the problem with conservative policy positions (at least in the US) is that they're mostly unchanged from 30-40 years ago. Despite mountains of evidence on things like work requirements for government benefits, multiplier effects of stimulus spending vs tax cuts, benefits of expanding healthcare coverage, and many more, the conservative positions remain the same.

I would guess this is likely because these positions are more based on philosophy than they are on actual economics or other evidence-based fields. This was a reasonable position when there wasn't strong evidence to either prove or disprove these arguments, but at some point the evidence becomes overwhelming, and those positions should no longer be considered serious. We're long passed that point on a number of issues, but it sure doesn't seem like anything will change anytime soon.