I understand that in a lot of big-lab fields it is common for the principal investigator to append their name to a paper even if they did not write the paper, design the experiment, or collect data since they spend energy securing funding, and managing the whole lab. What about for small labs?
What are the requirements for a supervisor to be included as an author on a paper, as opposed to just appearing in the acknowledgements? If you are working on your own projects independently of your supervisor, but using funding provided by your supervisor (how does this change when the funding provides resources versus just your salary), are you suppose to add them as authors or just acknowledge the source of funding?
You should of course research the norms for your specific field. However, in order to resolve precisely this ambiguity, it is becoming much more common in certain fields to have a section of the paper that actually specifies exactly what the author contributions are. The Cell Press and PLoS journals, among others, actually require the use of a defined vocabulary called the CRediT Taxonomy, first outlined in Brand et al., 2015 [pdf]. Some of the role descriptions include "Supervision", "Project Administration", and "Funding Acquisition" in addition to "Investigation", "Formal Analysis", and others relating more directly to carrying out the research itself. Compared to author order, which is a field-dependent and sometimes low-information indicator, this makes it much more clear why each given author was listed.