[WS:] True. It has happened in the past with the pro-lifers, as Thomas Frank noted in his book "What's the matter with Kansas?" They supported Republican "pro-life" agenda against their own economic interests, ad did not even get bupkes in return - just the campaign promises.
The same will happen with anti-immigration or cutting government spending promises. These are just hate buzzwords that make old white bigots happy, so politicians use them to get votes - but it is corporations not labor that benefit from immigration or most of government spending - so we will see more business as usual.
A logical conclusion from your observation is that in these times electoral politics is pretty much a professional wresting show - pure posturing, a lot of smoke but no fire, a circus to keep the masses happy. It makes no real difference to the great majority of the population - other than giving them a sense of symbolic victory of the kind sports fan enjoy when "their" team wins. It will change only if there is a material opposition to the corporate interest, by which I mean people who can control material resources in a way that can make capitalists scream. The commentariat and people stomping their feet in the streets and casting their ballots do not have such power, not even close, so they have zero impact on the political establishment - whether Republican and Democrat.
Wojtek