Incentives.

First X people that reproduce Y get Z percent of patent revenue.

Or something similar.

Most papers generate zero patent revenue or even lead to patents at all. For major drugs maybe that works but we already have clinical trials before the drug goes to market that validate the efficacy of the drugs.

Patent revenue is mostly irrelevant, as it's too unpredictable and typically decades in the future. Academics rarely do research that can be expected to produce economic value in the next 10–20 years, because the industry can easily outspend the academia in such topics.

I'm delighted to inform you that I have reproduced every patent-worthy finding of every major research group active in my field in the past 10 years. You can check my data, which is exactly as theory predicts (subject to some noise consistent with experimental error). I accept payment in cash.