If someone has that marginal an income, they will never even begin to start a savings plan, nor will that money survive to retirement. It will be gobbled up by the first medical or vehicular emergency that comes up.
Unless of course they live in a country that has tax-funded health care and useable public transport, of which there are quite a few.
He/she is talking about the UK, where the burden of healthcare costs are shared by all taxpayers and there are no nasty surprises after a visit to the emergency room.
Whereas I live in the US, where it is common to have to do a back of the envelope calculation whether to drive or take an ambulance. Pro tip: if you are conscious, you'll never take the ambulance.
I'd rather lose my savings in a vehicular emergency than lose my car and therefore lose my job and future income.