This is as it should be. But the reader of the article has no idea whether you looked at it or someone with a far less significant commitment to the task than y

This is as it should be. But the reader of the article has no idea whether you looked at it or someone with a far less significant commitment to the task than you. And what's keeping you and your friend doing this time-consuming work is your commitment to science and your sense of ethics and responsibility, which your community certainly does not universally and uniformly share. That commitment is also the first to go when career, money, lack of time, etc. start coming into the picture, or the pressure to abandon it is certainly high. That's what we need to find a way to alter: If you are doing great science -- including the painstaking work of carefully reading a paper and following minus signs through calculation and checking integrals and whatnot -- that should be explicitly rewarded in the profession, and shouldn't just rely on intrinsic values a researcher holds in order to survive. I don't see journals today being the leaders in driving that innovation.