Two things
1) Suing the US government only works when they say you can sue them (see: Sovereign Immunity). Additionally, the rank-and-file have vastly extended defenses against lawsuits (see: Qualified Immunity). If an customs agent decided to get especially frisky against you, the odds of you succeeding on a lawsuit against either the agent or the US government is close to nil unless it was an extreme violation of your constitutional rights, and even then it's not in your favor.
2) We have multiple recent examples of US citizens being illegally detained by ICE agents despite showing paperwork and evidence of citizenship. If you think you're safe: You're not.
1) There are very few compared to the scale of deportations currently being processed, so each case is exceptional against an incredibly low base rate. And these stories have been happening since 9/11 but journalists didn't give a shit until there was a salient political point to be scored
2) They are all suing the everlasting shit out of the government or have already settled
These are not normal times, and your cynicism is not serving you well here.
EDIT: I don't believe that the parent post should have been flagged. While I disagree with them, I believe they posted productively and in good faith.