Why do we accept low pay for key workers as the norm?

I agree with Peter and Elizabeth. Ultimately supply and demand will result in a balance point in the labour market. Once working environment, job satisfaction and all the other elements of an offer are in balance with what people are willing to accept, then jobs will be filled - even if for moral reasons we believe better pay and conditions would be more désirable.
If that balance does not exist, jobs will remain vacant.
Elizabeth rightly points out that budgets are not infinitely elastic, and that the willingness to fund salary increases through increased taxation or cuts elsewhere simply is not present - either in the political world or the working world.
In the UK there is a cultural tradition of light government financing in many of the areas where low-paid key jobs exist. I personally cannot believe that employees would accept 20% social security contributions and employers 50% (as in France, for instance) to bridge this gap.

These statistics on equality of income distribution may help paint the international picture:

data.oecd.org/.../income-inequality.htm

It's a complex topic I think in economics - partially but only partially yes it's supply and demand for labour but also it's to do eg with equality of distribution of wealth and Government policy / interventions re income distribution eg taxation; minimum wage etc.

Also, equality in terms of everyone being poor isn't necessarily at all the same as inequality but with even eg the poorest quartile being reasonably rich compared with the former - if you see what I mean.

However, overall, and probably for equally-complex historical political and cultural reasons the UK seems to well towards the higher end of the inequality indices compared eg even with nations such as Austria, but ultimately this is a social policy / political matter?

These statistics on equality of income distribution may help paint the international picture:

data.oecd.org/.../income-inequality.htm

It's a complex topic I think in economics - partially but only partially yes it's supply and demand for labour but also it's to do eg with equality of distribution of wealth and Government policy / interventions re income distribution eg taxation; minimum wage etc.

Also, equality in terms of everyone being poor isn't necessarily at all the same as inequality but with even eg the poorest quartile being reasonably rich compared with the former - if you see what I mean.

However, overall, and probably for equally-complex historical political and cultural reasons the UK seems to well towards the higher end of the inequality indices compared eg even with nations such as Austria, but ultimately this is a social policy / political matter?

Again I think we have to look to history for the answer as to why inequality seems the remain more tolerated in the UK than elsewhere David.

Post WW2 almost all the remaining European monarchies had been either decimated during the expansion of the German Reich or returned from exile to cultural infrastructures devastated by war and with social hierarchies similarly demolished. In the UK and its empire/commonwealth those hierarchies and integral respect tor social "rank" remained and have largely continued to do so to this day, albeit gradually decaying or being deliberately set-aside, but also transferring easily to corporate leadership and structures as well as previously to hereditary acquisition. The underlying acceptance of certain roles being low paid in financial terms though in some cases offset by other "benefits" has therefore also remained: The one time butler or housemaid providing ill paid but alternatively recompensed (by food and shelter) "key" personal services of care and convenience for their social "betters" now subconsciously replaced by the care-worker or delivery-driver providing key personal services of care and convenience for our sick and elderly, or high-street "consumer" and home-shopping customer.

On the other end of the scale this is also why we continue to tolerate (albeit sometimes grudgingly) the disparity between salaries and disproportional taxation seen partitioning our "shop floors" and Boardrooms, and have continued to accept Government policies (from both parties) that failed to address (or at times enhanced) those inequalities.

Our lack of urgency regarding, or even recognition of, financial and social inequities are therefore not because we perversely don't care about them as much as other nations, or would not be a fairer and possibly happier society without them, but because we have been brought up within them and familiarity presents a far more comfortable acceptance than they justify or deserve.

P