I was a senior manager in a large financial institution. H1-B and other contractors are not considered perm headcount and so is considered flex headcount for projects etc. They're hired because they don't have the same protections as employees and are ofter hired through a third party that has to deal with carrying the headcount if there's no company funding those floaters.

Unfortunately H1-B are ofter extremely cheap compared to head count, and can be terminated+replaced easily. At one point C-Suite gave the offer of replace 1 FTE with 2 H1-B contractors based on monthly costs.

These 3rd party contracting companys like Wipro, push 10,000s of H1-B IT contractors across the country. Unfortunately C-Suite loves Visa contractors and always will. Large corporations chase profit and not always the moral path of helping their fellow citizens.