Because the general population will pay regardless.
It's a case of making us pay and losing established businesses, which will still cost the government, or supporting them until longer term (nuclear, solar, wind etc.) solutions can be created.
If every pub, restaurant, cafe etc. closes down it's not just a loss to the owners and workers. It's a loss to the government. All those people will go from net contributors to claiming JSA or similar.
For context, were I on JSA I could claim a maximum of £880 a month. My rent burden is £500, my standing bills in contract (internet, phone etc.) are £55. Water is £30 a month. Electric and gas are currently £100 and set to triple. Once that price rises that's £885. If I lose my job to this I would cease being a net contributor, I pay monthly about £550-700 in tax and NI, not even counting VAT. So the government would be losing out on £1450+ per month, per employee like me just so those people can live in abject poverty.
It makes far more sense to use that money to support existing businesses, unless their end goal it to gut them, buy up properties on the cheap and then further funnel money to the top 1% when(if) they become viable again.