Over 80% of sunscreen performed below their labelled efficacy (2020)

Agreed. The free market solutions to this problem are completely ineffectual. Nobody is paying a 3rd party to test sunscreen and even if they were, the results wouldn't likely be public and/or would be buried under the giant weight of mommy influencer blogs telling you to use apple cider vinegar instead of sunscreen.

The only way to solve the problem of bad actors in a consumer products market is government regulations, testing, and fines/dissolution of the bad actors.

Not the only way. There used to be 3rd parties defending consumers by testing products back in the days, and publishing their results, not sure if those still exist today. The problem with mass manufactured products is that you need to keep testing them. Changes in formulation are a thing so you need to continuously sample and test them.

The problem with government being involved is that this opens the door for easy corruption (haven't we seen this before)

> There used to be 3rd parties defending consumers by testing products back in the days, and publishing their results, not sure if those still exist today.

CHOICE in Australia does this, and was the group that did the efficacy tests on a bunch of sunscreens sold in Australia where they found that many were massively underperforming.

> There used to be 3rd parties defending consumers by testing products back in the days

And what happened to them? Why did they go away?

It wasn't due to the government outlawing them.

> The problem with government being involved is that this opens the door for easy corruption

And 3rd party reviewers aren't easily corrupted? There are at least some mechanisms to address government corruption in a democracy (elections). What mechanism can be employed against a 3rd party reviewer that simply lies about a product it's reviewing?

That's the reason this has to be government ran. Corruption happens regardless of who's doing it, government at very least faces some accountability.

The question is always, where do those third parties get the money to do their research?

If you are against the government funding them, where do you suggest they get their money?

A company like Consumer Reports was funded by subscriptions to their reports, but they don't make enough from that anymore to test enough products.

Another issue is the sheer number of companies producing products these days. It would be very expensive to test all the products sold.

> The question is always, where do those third parties get the money to do their research?

in the 80s they were selling magazines.