Independent lab testing of consumer packaged goods is so important, expensive, unprofitable, and downright risky from a libel standpoint that I dare say it should be the role of government to do it.

You essentially describe the motivation for Stiftung Warentest [0]. They’re massively successful in Germany, and I rely on their tests for many consumer goods I buy. Access isn’t free though, typically costs around 5EUR per test. Coincidentally, they recently tested sunscreen [1].

[0] https://en.m.wikipedia.org/wiki/Stiftung_Warentest

[1] https://www.test.de/Test-Sonnencreme-und-Sonnenspray-fuer-Er...

Feels like one of those classic cases where the market alone can't sort it out, and strong public infrastructure should step in

And yet we are going in the exact opposite direction.

Yes, because government inspectors are flawless and would never take bribes to let things pass or force them to fail. Nope, they'd never do that.