It's not the same because a patent is a time-limited monopoly on a technology. This means that patents can be used to block the progress of other companies.
E.g. if A patents X and some large company B wants to use X and A refuses, then B cannot use X even if they offer millions.
You are also right. I was responding to this. (Italics mine)
> Like, if the government (or anybody, really) wants an invention to be open,
The government literally does want inventions to be open. It's in Article 1, Section 8, Clause 8 of the constitution. [0]
[The Congress shall have Power . . . ] To promote the Progress of Science and
useful Arts, by securing for limited Times to Authors and Inventors the
exclusive Right to their respective Writings and Discoveries.
> E.g. if A patents X and some large company B wants to use X and A refuses, then B cannot use X even if they offer millions.
How does this situation improve in any way if X is a trade secret? Under what circumstance would company A be willing to accept payment to make X open, but not willing to license X as a protected patent?
It sounds like you'd be in exactly the same situation except that there would be a massive collective action problem trying to figure out how much the world should pay A to make the invention open and who should pay it, and also A and B would have multi-million-dollar incentives to engage in corporate espionage and counter-espionage that achieves no progress.
E.g. if A patents X and some large company B wants to use X and A refuses, then B cannot use X even if they offer millions.