We have unfortunately created an internet (and to a larger extent, a global society) that runs on material wealth. In depth product reviews take time, and time is money - shit is tough out there, and nobody wants to work this hard for no material gain. Add on to this the inherent signal boosting on platforms like Youtube, Facebook, and Twitter (where reviews like this are usually posted / discovered) that will favor product reviews from channels that are monetized or that have paid directly for visibility (for example, from an ad agency). You're much more likely to see an ad disguised as a review than you would stumble across a genuinely unbiased review.
In the past, people would subscribe to something like Consumer Reports and the subscription revenue alone could sustain them providing unbiased reviews for lots of different products. They're still around and apparently unbiased, but I don't believe their claims because I'm a cynic and their website looks like pure clickbait.