I say again: if I were to propose a large hike in council tax, or a large cut in other services, so as to be able to subsidise a municipal airport, then guess what ... I'd lose my seat, and not be in a position to implement such a policy.
It's called "democracy". It's the UK voters who don't want to subsidise what they see as a rich man's hobby. One can only assume that voters in other countries take a different view.
1. I find it somewhat unlikely that an election would be decided on that particular issue only. You'd come under criticism from someone, sure, but politicians come under criticism for how they tie their shoe laces anyway, so...
2. While there might be exceptions in a big country far out west, I think it is rare to see an instrument airport with 2,000+ m of asphalt being built solely to cater for rich men in PA28s...
In countries where airports are subsidised, you'll see government money spent on airports with scheduled traffic that form part of the countries' national infrastructure; communities and regional administration spending money on smaller airports where they might
want scheduled traffic or to cater for taxi and business travel, considered vital parts of the community's or region's infrastructure; and at most token sums to non-instrument (= non-commercial) airports with <1,000 m runways (i.e., the "rich men's toys" airfields...). The idea to build a mini-Heathrow using tax money for the sole purpose of handling light GA traffic would be equally bizarre to voters outside the UK! It's not done that way.
3. Subsidising is only one way to keep landing fees down for light GA, and not the most important or desirable one. The way to go, and how it is done elsewhere, is to better differentiate landing fees in such a way that small planes don't get to pay huge fees for services they don't need. With the current British system, light GA daring to set foot on a large regional airport
subsidise the facilities that only larger aircraft need. And then I'm not talking about hard runways and fire support; I'm talking about 2,000 meters of runway and CAT 7 fire support for a PA28.