people fund the NHS in their younger years by not using it much, because they're healthy. When they age, they're less healthy, and that's when they need more prescriptions. Penalising the sick is what the NHS was brought into being to avoid.
Fuel allowance could be rationed to those in need, though. Possibly TV too, though I doubt making rich over-75s pay for licences is going to rescue the economy.
But why not just collect tax from businesses instead? If Tesco paid what it should, it would cover TV licences for everyone in the land.