Should a bachelor’s or master’s thesis include acknowledgements? For Ph.D. theses, I think nobody would disagree with adding acknowledgements. But what is the stance in different places for a bachelor’s and/or master’s thesis?

When I was doing both, I strictly followed the guidelines laid out by the university which required me to include an abstract in both English and German, introduction, results, discussion, experimental details, a table of contents, a statement that it’s my own work and an appendix (which included literature, copies of the NMR spectra and Perl scripts) — acknowledgements weren’t mentioned anywhere. (The Ph.D. student whom I was working with during the bachelor’s thesis and the subgroup leader where I did my master’s were included in the statement that it’s my own work.)

Now, during my Ph.D. work at a different university, a lab colleague is finally completing his master’s thesis and has different samples from former master students. Most of these included acknowledgements (even though they often didn’t say much).

I found one site with a non-representative poll which was in favour of not including them, the reason being the duration of the work just being too short; but that’s merely anecdotical, not representative.

So outside of universities where either version is required, should a master’s or a bachelor’s thesis include acknowledgements? Is there any kind of general practice?
Acknowledgments are almost always an optional part of a document that you can choose to include but don't have to. This is true for PhD theses as well as MSc, Diploma theses, or any other kind of document.

The guiding line is: If there are people or institutions who you feel you want to thank or acknowledge their support, then do so. If you think that everyone in your life and your university has let you down, then don't.