Suppose you were running a business that offered a service, hairdressing for example.
You've worked out all your costs of running the business and have come up with a price list for your services, which your customers are paying.
Then the government announces that everyone over 40 will be entitled to free haircuts from any registered hairdresser. Your rival businesses register and many of your customers defect to them in order to get their free haircuts. So, you have no option but to register as well, in order to keep your business afloat.
You then discover that you get paid a fixed amount for the free haircuts that you provide under the scheme - and the amount is much less than what's on your price list.
Your price for a haircut is, say, £45, but you only receive £30. So you have a shortfall of £15. You feel you have no option but to increase the price of haircuts to your younger customers (those under 40 who aren't eligible for the free cut) to £55. So then your younger customers and the business itself are effectively paying part of the cost of the so-called "free" haircuts.
Each year your costs increase (rent, rates, energy, staff salaries etc) and the amount you receive for the free cuts doesn't keep up. You have to start charging your customers for "extras" that used to be included in your haircut prices.
And so it goes on. Eventually, if you want to keep your business running, you have to introduce a charge for those accessing the free haircuts. Maybe they can now only have the cut if they book a blow dry or some highlights at the same time.
All this time, the government bangs on about everyone over 40 being entitled to free haircuts. Those supplying the cuts and those accessing them know that there is no such thing and what they actually have is a subsidy towards the cost of a haircut.