I think the third option is more plausible; neither executive decree nor individual managers' particular penchant drives these trends, but rather widespread cultural trends that individual managers act on subconsciously.

We're likely talking about favoring H-1B visas; predominantly Indian, and predominantly male, with a median age of 34.[0] Do individual hiring managers have individual, personal biases? Yes, but what do you call a collective group who all exhibit the same bias? We can speculate about their personal reasons, but keep in mind that H-1B workers are inordinate victims of wage theft! [1]

> Thousands of skilled migrants employed by HCL Technologies—an India-based IT staffing firm that places H-1B workers at top corporations like Disney, FedEx, and Google—appear to have been underpaid by at least $95 million

So perhaps it is simple economics: precarious immigrant workers are easier to steal from.

0. https://www.uscis.gov/sites/default/files/document/data/H1B_...

1. https://www.epi.org/press/new-epi-report-reveals-wage-theft-...