That's because they aren't beliefs. The characteristics of "political beliefs" most closely match up with the concept of policy. Political policy, however, implies that they are malleable, and though they are and do frequently shift, politicians would prefer that you see them as more concrete than that so that they have a social buffer to fall behind to resist the public erosion of those political (largely party) policies.

See I feel the same way about Halloween. Where I'm from, we have more communal Halloween time/ harvest parties and the whole community participates in Trick-or-Treating. there are ads and events and people talk about the scary movies they're marathoning. It feels very communal, Maybe even more so than Christmas, which for us is mostly family centered. It's a feeling that I just catch every year.