I suppose standards about acceptable practices for undergraduate research projects vary from institution to institution and across countries. I do have a few observations of my own, based on an admittedly very, very small sample of institutions in one country.
I have worked at a university where we had the staffing and resources to give students introductory stats training and an introductory methods course - the latter usually taken during the Junior year. None of those projects was ever intended for publication, given the small samples involved, and given that students were expected to produce a finished research project in one semester. At my current university, my department requires students go through an intensive four-course sequence of statistical and methodological training. Students are required to learn enough basic stats to get by, learn how to put together a research prospectus, and then gain some more advanced training (including creating and managing small databases) in statistics and in methodology. The whole sequence culminates with students presenting their finished research on campus. That may seem like a lot, but by the time students are done, they have at least the basics required to handle developing a thesis prospectus in grad school. At least they won't do what I did and ask, "what is a prospectus?" That was a wee bit embarrassing.
Each fall semester, I write a general IRB proposal to cover most of these projects for my specific course sections. That IRB proposal is limited to a specific on-campus adult sample and to minimal risk designs. None of those projects covered under that general IRB proposal are intended for publication. Students wanting to go the extra mile need to complete their own IRB forms and gain approval. Students who are genuinely interested in my area of expertise go through the process of completing their own IRB proposals and dealing with any revisions, etc., before we even think of running anything.
Only a handful of those have produced anything that my students wished to pursue publication. To date, I have one successfully published manuscript with an undergrad, one that was rejected (it was an interesting project, but admittedly the sample was small and findings too inconclusive), and one that is currently under review. That these students were coauthors means that they contributed significantly to the writeup. That means my peers could grill them at presentation time and they could give satisfactory answers. They knew their stuff. And the reason they knew their stuff is because I went out of my way to make sure that they were mentored as they made those projects their own. I made sure that I had seen the raw data and worked together with each student to make sure data were analyzed correctly. I stick to fairly simple to accomplish personality-social projects in those cases as that is my training. That's just how we roll.