It’s just a matter of climate. In Ireland temperatures above 20C are rare; they happen only a few days per year. So for most of the year we need to heat our houses, not cool them. The climate in the UK (and most of northern Europe) is not quite as moderate as it is in Ireland but the point remains that cooling air in houses is only needed for a small part of the year.
A proper central heating system with radiators and a thermostat certainly allows you to control temperature, though it’s a bit slower to react than air conditioning.
It’s probably a cultural as well as a cost thing. Traditionally in Europe we have used radiators to heat our houses. Air conditioning was very expensive for domestic use and was seen as a luxury to cool the house in summer.
I’m sure air conditioning is much more popular in southern Europe.
Personally I much prefer a radiator over an air conditioning unit, partly because the temperature change is more gradual and because I don’t like the constant air flow but it’s mostly because it’s what I’ve been used to all my life.
Because radiators provide better heating than forced hot air.
Look at older commercial buildings (>60 yeas old, before AC was commonplace) — generally they have radiators. The heat is awesome when it is cold. I have lived in many places, some with FHA, and some with radiators, which I have now. Radiators just win.
You install HVAC when you need to heat and cool because it is cheaper to have only one system. But if you have the money, you have two systems, radiators for heating and HVAC for cooling. Radiators are that good.
If you are building new, the cost to install FHA system and radiators are about the same. If you don’t need A/C because of the climate, then go with the better system, radiators.
Lately the in-the-floor hydronic systems are available, and they are even superior to radiators. You can lower your thermostat by 5 F because of the heat conducted through your feet keeps you warmer.