https://assets.publishing.service.gov.uk/government/uploads/...
4.3 Explaining the Class Pay Gap
In order to disentangle potential sources of the class pay gap we next use regression analysis to see how the gap is affected when we adjust for five sets of factors often identified as sources of income inequality. Figure 3, begins by showing (in the first bar) the raw average earnings gap reported in Figure 2, while the second bar shows the average earnings gap in pounds per week when we control for gender, ethnicity, age and hours worked. In the next bar, additional controls for educational attainment are included; then human capital, work context (work region, industry, firm size, public vs private sector) and finally the individual occupation the individual works in.
[..] even when we control for all of these variables, Figure 3 shows that the class pay gap remains substantial and statistically significant (see Appendix Table A10 for standard errors). Thus even when those from working-class backgrounds are similar to those from advantaged backgrounds in every way we can measure, they still face a 7% or £2242 a year pay gap in Britain’s professional and managerial occupations.
“Class groups including “working-class” are based on parental occupation aged 14”
[1] https://departmentforopportunities.org/news/the-class-pay-ga...
So, now, the situation is that you have seen a study with results that you don't like, have come up with a reason why the conclusion is invalid without even checking if the conclusion is indeed invalidated by this reason, and used it to reassure yourself and attack the study.
In this case, you are clearly the unscientific irresponsible here.
It's pretty irresponsible of the Guardian not to even interview a single labor economist who can explain this to their readers.
Instead, they interview lawyers and politicians who are denouncing the very mechanisms that lift people out of poverty, because it is by taking advantage of this that wages in poorer areas go up:
If a business had to pay the same wage in the rich and poor area, then there would be no incentive to increase hiring where labor costs are lower, and this is exactly how you bid up wages in those areas.