A skilled job requires a skilled worker - and in highly skilled jobs, the more skilful a worker the better or faster they can do the job. An unskilled job generally just requires an average persons labour.
A worker in a skilled job can negotiate their pay according to the unique level of skill they bring to the job, and so how well/fast it is completed.
A worker in an unskilled job generally just has to be there, anyone will do, they are a commodity to fill a slot.
Skilled jobs are paid according to the skill of the specific worker, unskilled jobs are paid according to the minimum required to get someone to turn up.
In the past employers would pay unskilled (and low skilled) workers a fixed rate that would have been established in the specific 'trade' by tradition and negotiation - maybe even a rate of pay according to the individual, maybe based on circumstance, length of service etc.
However with the introduction of a national 'standard' for low pay (the minimum wage and the living wage) this has all been swept aside - there is no reason for an employer to even think about (or negotiate) a rate - they can simply cite minimum (or living) wage and there is an end to it.
Accordingly these have become the maximum wage for huge chunks of the working population - with no prospect of improvement, progress, development.
Minimum wage is bad enough - but Living wage takes this to a new level. People know minimum wage is a pretty poor deal - but they imagine living wage is a fair deal, and companies supporting it get feted for doing so. However, living wage has been set so a member of a childless couple gets far more than the 'need', but every other type of individual (single with or without children or in a couple with children) gets far less than the Living Wage foundation have *themselves* calculated the need.
Minimum wage can be campaingned against - everyone understands that! But Living Wage is just as bad, but it (bogus) reputation means opposing it gets you classed as a mean bastard!
Living Wage is newspeak to let employers rip off employees and get praised for doing so! Don't be fooled.