Presumably Infosys also pays citizen workers shitty too. The issue here is Infosys, not h1b.
I will also add a data point for big tech. I have managed people on h1b, on o1, with green cards, and citizens. I have never even sniffed any sort of disparate treatment across these groups once hired. During hiring the bias was against h1b since it was a huge pain in the ass to arrange everything and their start date could be delayed.
Infosys has virtually no citizen workers, and the ones they have are managing entire programs - they aren't doing client work. The only reason they have any workers at all is they can't realistically change H1-B sponsors.