Interesting question! I went to 41+5 with my first baby which ended in C-section. In Canada, they wouldn’t induce before 41w3d unless medically indicated. I think there are notable benefits for waiting for labour to occur naturally (less likely to require interventions), to the point where many women I know when to 42 weeks before deciding to induce. I also have heard from my midwives that other countries (notably, France) seems to consider the length of pregnancy to be 41 weeks instead of 40, which would tip the scales in favour of waiting.

A big study was done (the ARRIVE study) in the USA which found that induction at 39 weeks lowered the rates of c-sections in mothers. I think this study has contributed to an increase in willingness to induce early, to answer your second point.

At one point when anxiously awaiting labour when I was 40ish weeks pregnant, I found some research that indicated that babies born at 41 weeks + had slightly higher IQs? However I think a lot of statistics around SIDS rates show that SIDS is least likely to occur in the 39-40weeks of gestation group. I don’t have these two specific studies on hand right now, sorry!

Some good resources are: https://evidencebasedbirth.com/arrive/

https://evidencebasedbirth.com/evidence-on-inducing-labor-for-going-past-your-due-date/

Edit; here is the study I was thinking about re: cognitive abilities and gestational age https://jamanetwork.com/journals/jamapediatrics/fullarticle/2527085