Firstly, despite all the media attention on Trump's racist immigration proposal, it was actually the Bush and Obama administrations that actually formally put racism into immigration policy. Under Bush, "NSEERS" (since eliminated) put registration requirements on nationals of specified countries -- see https://www.federalregister.gov/arti...-system-nseers -- every single one of which was Muslim. The Obama administration implemented requirements that citizens of visa-waiver countries born in a similar list of countries be required to get a visa.

More recently, Congress has passed entirely racist changes to the visa-waiver programme.

In my personal experience, I have not encountered racism (I'm white European), but I did have an agent openly acknowledge using sexist profiling as the basis for searching me -- I had Thai stamps in my passport, and I was informed that they scrutinise single males (but not females) who have travelled to Southeast Asia.

I have no problem with a travellers being subjected to intensified scrutiny based on their specific, personal circumstances. But the participation, for example, of a handful of Algerian-born French passport holders in ISIS should not be used to subject ALL Algerian-born travellers to extra scrutiny, nor should handful of males travelling to Southeast Asia to have sex with minors be used to justify the harassment of travellers solely on the basis of their gender and their past travels.

And we also know from whistleblowers that racist attitudes are endemic in CBP, with -- amongst other things -- wearing hair in dredlocks being used to justify intensified scrutiny.

So no, we cannot look inside the mind of the agent responsible for this harassment and know what made him/her decide to harass this passenger, but given the context it's not unreasonable to assume that racist motivations came into play.