Expecting racists to be so blind to the consequences of explicitly showing racism in public seems a ridiculous move.
It's not the 1970's, anymore. Public acceptance of people who are openly racist is all but gone.
That doesn't mean racism doesn't exist, anymore. It just means being open about it is suppressed.

It's no longer culturally accepted to be openly racist in public, true.
Humans gonna human, though.

Opposing immigration is not necessarily racism. Racism can be a part of it or not. Controlling your nations borders isn't really a partisan issue. No one's suggesting fully open borders or that the country doesn't have a responsibility to know who's coming and going, or that the country should be without any limits on immigration whatsoever.

I don't doubt that plenty of people calling for border controls are motivated by racism, but is it conscious, open, out loud racism? Almost certainly not. People don't see themselves as the problem. That doesn't mean they aren't.