Why there is no enforcing body in validating contributions?
Actually the &quot;enforcement mechanism&quot; is the entire academic community. Papers, for the most part are written by specialists, often for other specialists. Every reader can make a judgement about both ethical concerns and contributions. Every reader can criticize any paper that they read.
One problem with a &quot;centralized&quot; scheme is that the expertise is so varied that it would take a gigantic organization to do so. That &quot;gigantic organization&quot; is the entire scholarly community.
Moreover, as to contributions by individuals in joint papers, that is probably best left to the authors themselves. Most journals insist on some form of agreement among authors in this by asking them all to &quot;sign off&quot; on the paper.
And your judgement about what is a &quot;minor&quot; contribution vs a &quot;major&quot; one might well differ from mine. But this is because there is so much variation in the kinds of contributions: time spent, &quot;effort&quot;, key ideas, writing, organization, creation of the enabling lab, ...