Labs generally specialize, as there's a long learning curve to climb before you can reliably execute even 'bedrock' molecular biology protocols like immunoassays. Small ambiguities in protocol can lead to failure, and there's always simple human error involved that can tank a result. Generally you'll have positive controls available to tell you whether a protocol was successfully executed, but there are cases where that's simply not practical.
In the end, 'failure to replicate' does not necessarily mean there was anything wrong with the original work. Positively concluding that requires a lot of additional work that could explain the discrepancy.
“Here, I did this magic trick, but I’m unable to tell you sufficient detail for how it works!”
Also, I found it interesting that even though computer science research are usually easier to reproduce, a lot of journals and conferences do not mandate artifact evaluation, this is just considered nice to have for submission. If we can have mandatory artifact evaluation, even something not reusable and can just repeat the experiment in the paper, it will be much easier to verify the claims in the papers and compare different approaches.
Not generally, though the tide is slowly turning in the right direction. Unfortunately many laws/policies pushing for openness and transparency in research are sidestepped with the classic "data available upon request," a.k.a. "I promise I'll share the Excel files if you email me" (they will not).
Possibly in some medical or social science fields, I don't know. I know there is not such an issue in chemistry and materials science. There also may be some complications for collaborations with industry, but that's kinda a different situation. For people whose career development is not strongly tied to reproducibility of their work (a.k.a. everybody) it's just another step in the overly complex process of publishing in for-profit journals. Funding agencies generally aren't going to punish people for using this excuse and the watchdogs/groups concerned with reproducibility have no teeth.
Not an excuse, but journals don't make it easy to share files, as hard as that is to believe. Some will only take PDFs for supplemental information and many have garbage UIs, stupidly small file size limits, etc. Just uploading to a repo (or tagged release) on GitHub is common these days because there is much less friction.
In fact, for most of the people in a position to ask the kinds of questions that need to be asked, they risk their entire career when they do so.
The entire industry has issues.
On the one hand you'll eventually get caught, but only after potentially millions has been spent on said catching.
* People not checking
* People checking and joining the fraud
* People checking, not joining the fraud and then getting their work suppressed.