Government bonds are only low risk in economic theory. In real world practice lending to left wing countries can be high risk as they like to accumulate too much debt and then default. That's why the UK government is paying 5.8% on its bonds at the moment despite being able to print its own money, which is the same average interest rate paid by Thames Water. Lending to Thames is not seen as riskier than lending to the state, despite that Thames faces huge regulatory constraints like price controls and the British government can literally force people to give it all their money.

> private companies draw down new debt on promise of future cash inflows from consumers

This is what governments do too.