For one thing, only industry executives are currently set to testify. And most of them are lawyers and policy experts, not engineers versed in the mechanics of data-mining algorithms.

Companies are sending their “policy and law folks to Washington to make the government go away — not the engineering folks who actually understand these systems in depth and can talk through alternatives,” Jonathan Mayer, an assistant professor of computer science and public affairs at Princeton University, told me.

That may be because Congress is under industry pressure.

California recently passed a new privacy law that would give Californians some power over the data companies’ hold on them. Industry groups hope to defang that statute by pushing Congress to pass federal privacy legislation that would overrule state laws. The industry-stacked Senate hearing lineup seems designed to pave the way for that, said Danielle Citron, a law professor at the University of Maryland.

Frederick Hill, a spokesman for the Senate Commerce Committee, said the group planned future hearings that would include other voices, such as consumer groups. But “for the first hearing,” Mr. Hill said, “the committee is bringing in companies most consumers recognize to make the discussion about privacy more relatable.”

What is at stake here isn’t privacy, the right not to be observed. It’s how companies can use our data to invisibly shunt us in directions that may benefit them more than us.

Many consumers know that digital services and ad tech companies track and analyze their activities. And they accept, or are at least resigned to, data-mining in exchange for conveniences like customized newsfeeds and ads.

But revelations about Russian election interference and Cambridge Analytica, the voter-profiling company that obtained information on millions of Facebook users, have made it clear that data-driven influence campaigns can scale quickly and cause societal harm.