This is the essence of it. While EU261 is well intended from a consumer point of view, it is fundamentally flawed that it puts the blame squarely on the airlines, and does not include service providers (airports, ATC, etc) higher up the food chain. Airports are natural monopolies, no matter whether ownership is public or private, and will only spend money on things they are compeled to do so.

[cynicism]There is no financial incentive for UK airport operators to invest in de-icing/snow clearing equipment. If they have passengers stuck in their shopping malls, I mean terminals, they are still making money.
Meeters and greeters are still paying for parking while waiting for delayed pax and the airport is still making money. [/cynicism]

Where I work we had 30cm of snow last Monday afternoon/evening. The airport slowed to a crawl but there was always at least one runway available. There were many diversions and cancellations but there were still about 600 movements (50% of normal January day) and yet there were complaints that we should have done better.

They were still scraping compacted snow off the taxiways yesterday after 4 days because temperatures never got above -10C and spent a lot of time around -20C (-30s with the wind chill). Because of the cold, ground crews had to go inside regularly to warm up and arrivals weren't parked for up to a couple of hours because of the extended time needed to service each flight. Inbound flow control was necessary to avoid gridlock. There were up to 30 flights on the ground waiting for gates!

Bad weather is expected here, we have the equipment for it and still it causes disruption.

https://trid.trb.org/view/1436898

$53m to install and $8,250 for each hour of operation

We had an interesting meeting with LGW airfield ops team a few years ago where we asked many questions related to operations in cold weather/snow.

One issue here, and the reason they have a back to black policy, is due to the temperature. When it snows here the temperature is normally around 0 degrees so the state of the snow is always changing, which means by the time you pass a runway contaminant and depth it has changed. To avoid any potential law suit they ensure the runway is clear.

Or make the airports pay who are responsible for keeping the airport open, not its users (airlines).
Then airport money has to be used for either equipment or compensation claims.
Airlines should not be burdened by the airport's lack of capability

To answer JimJim1 and others.
The UK is in a 'maritime' climate zone and its climate is driven by the Atlantic. The Atlantic affects most of North West Europe but to a lesser extent. The Atlantic has what is known as the Atlantic Multi-decadal Oscillation (AMO). For the last few decades the AMO has been in its 'positive' phase that is the water is warmer than 'normal' there are some indications that it is about to move into its negative phase and everything will cool down. See the diagram below
https://cimg5.ibsrv.net/gimg/pprune....cdccbe7d61.png
While this does not explain all the weather as the cool ocean also affects (and is affected by) atmospheric circulation it does raise (or lower) the chances of precipitation in the winter falling as snow in UK. As it is multi-decadal an entire career can exist in one phase of the AMO. So it is not simple to just 'rely on experience' due to our fleeting existence. Also, linear projections do not work on sine waves, so just because we have worked all the time on the rising side of the sine wave seeing less and less snow, we cannot assume that there will not be a descent back in a few years with more and more snow.