Farming subsidies are one of the most criticized parts of the EU. My comment isn't in support of it. But even so, subsidy is quite different from compulsory purchase. The question is: why is steel special. Not in a no-action-vs-some-action way, but why so aggressive?

Ironically I think it's the same for both steel and farmers: they provide votes.

Because like, every basic war machine is made from it? Like how is this a question?

There's been two world wars and access to or stockpiling of steel has been a critical strategic factor in both.

Most consumable military assets are made from steel, for example and it underpins most machine tools and factory components as well.

For lots of reasons but if you're the UK and you're honest with yourself and you are only allowed to pick exactly one reason that steel is absolutely critical?

Royal Navy.

Farming subsidies are the only way to prevent famine, the granary system sort of works, but regularly resulted in shortages and famines throughout every empire in history. Even not accounting for longer term climate trends, yield due to weather can vary up to 30% in a year, so it only makes sense to pay for a bit of over production so in the event of a couple bad years your food output is merely break even, and not 70% of needs.

Its better to pay 5 cents more for a loaf now than pay $20 a loaf with rationing later, or if we went back to granary system possibly getting moldy food.