The problem is you also see this behavior in well established lab, where the PI has very little to lose if he quits research altogether.
In my experience, the correlation with whether the professor was an assistant professor seeking tenure vs a well established full professor and the amount of work they make PhD students do is almost nil. It's mostly purely driven by the will of the PI, not the demands of the funding situation. A lot of professors choose to have few graduate students so they don't have to stress too much about funding.
Remember: Once you get tenure, your job is not at risk if your research output is low (although it does affect compensation). If you get a $1M grant and end up with no research papers out of it, there is no accountability - except the granting agency will deprioritize you in the future (if even that).
If you're seeking an advisor, ask his/her current students what life is like. Also find people who graduated under him/her and ask them.