If you're a resident, they eventually have to let you in. But if you aren't, they can reject you for any reason. This isn't something you can solve with tech. Those of us who are citizens of the US need to vote for politicians who make privacy a priority, and be more politically active in general. I feel like you could even make the play that it's bad for business, because it's impeding business travel. You could even point to this very post as evidence that many companies consider it a Big Deal - the idea that they have to explicitly hide their company secrets in this way because border agents are out of control.