That's only partly true:Just to clarify the terminology here.
The government aren't "contributing" to anyone's pension. The government don't create any money/wealth, they appropriate from one party to another.
By contributing to a pension you are deferring recognition of your income.
Therefore the government are simply deferring their appropriation of that income by means of tax.
They'll get that tax later, under whatever regime and rates are ruling at that time.
- You are ignoring the tax free lump element of pension schemes
- You are ignoring the fact that some retirees maynot be liable for any income tax in retirement or may only be liable for income tax on a small portion of their retirement income.