As a grad student so far though I've found the incentives to be very locally driven and the kind of research you can do is almost wholly determined by yourself and your advisor. This can be good or bad but if you find an advisor who is in a stable spot (tenured or nearly-tenured) and not a jerk they'll generally give you leeway to pursue what you believe to be high-impact work even if it doesn't align with the general consensus on what to do next, especially if you have proven credentials and a clear image of a research plan in mind. Additionally progress is largely driven by the individual so there's a larger personal motivation to really delve into a problem and be consumed by it. For me personally, I have access to significantly fewer resources than before but have gained the freedom and time to not be attached to the paper-mill or some measurable metric and am spending months of my time trying to get at a deeper problem than I ever would have been able to in industry. While this may be different than the usual narrative about academia, I think it's more true than people say since there are such huge variations in how academia works as a result of school, advisor, and the individual researchers themselves. The disgruntled tend to be those who complain the most while those happy with the field are busy doing other things. I'd compare my experience in academia thus far to the startup of the research world whereas the industry jobs (at least in tech) consume far more resources and are pressed to provide steady, measurable impact. Maybe it's upsetting that we do waste some resources on stupid research which does exist, but the odds of getting a researcher like Einstein dedicating 10 years to discovering relativity in an industry job are vanishingly small. I'll probably be unsuccessful but there are 100's of people in my field doing related but different approaches and this kind of swarm approach is more likely to give a fundamental discovery on a population level than the large alignment of goals found in private research who would do a great job building on any basic science discovered in academia. I don't think it's wasted resources if 99 researchers fail in different ways and 1 succeeds since traversing the tree is inherently valuable even if most of the leaf nodes are failure. That's far more likely to happen in academia imo than industry.
It's not that private sector funding is inherently worse, but in reality it is different and as such will lead to different results due to how people and our economic system at large work. While I'm sure there are exceptions where individuals at private research labs are highly-motivated and feel the push to go the extra mile and try to find some deeper truth than is necessary for their personal well-being, in my experience many doing research at these companies are apathetic as a direct result of the environment in which it's being conducted. It's hard to feel motivated to make a large step in basic science when you think it'll just be consumed by the large institution you exist within who's stock price you have no real effect on rather than being open-sourced for peoples' benefit. We should have diversity in how we fund science.
Or maybe it is a problem with the structure that fosters an environment. What comes to my mind is the exceptional case of OpenAI, which started as a nonprofit. Sure, it "ended badly" because of the known drama, but my guess is that besides the money that was poured into it, it thrived because researchers had kind of an "emotional safety net," meaning that they wouldn't be pressured for results as much. Probably the reason some startups perform much better too.
I think career continuity matters, and you don't necessarily get that in the private sector for sure. This discontinuity then leads to practical work discontinuity, which means less work done (which is amplified by the non-decentralized nature of working in private compared to shared science in public, as you've explained).
My bottom line is that the private field could do better, and frankly it's kind of their loss. What I'm curious about is whether a "semi-private" approach is better: a non-profit or some kind of foundation. I guess in practice they're still private, but whether the money part can be "solved" through crowdfunding/some modern methods and whether they're viable long-term remains to be seen. One thing is for sure: a culture appreciative of science will definitely open more doors into novel methods of funding and organizing (maybe in the future these methods could rival the "traditional ways" of public science).