I think it sounds like a serious problem that is underreported. My electrologist, who is very trans experienced and has been doing hair removal for trans women for decades, told me not to believe any doctor who told me that "scraping" was enough to remove all hair follicles. She explained that she has had clients from most of the big-name surgeons and that several of them who were told not to have electrolysis ended up with vaginal hair, which could sometimes be removed and sometimes was too deep for anyone to get at with a probe. Again, this includes patients who went to doctors who "guaranteed" scraping was enough. Apparently it's almost impossible to remove all hair follicles with one pass of anything, and while it doesn't happen to everybody, the risk is enough that she encouraged me to not even consider SRS without a year of genital hair removal first, which I am in the middle of now (which is just as well as my doctor requires genital electrolysis.)
For me, it's a no brainer. The additional 8-12 months of occasional electrolysis treatments to ensure I won't end up with a hairy vaginal interior is a tiny price to pay for a good result. The idea of having to pluck hair from my vaginal interior or douche with Nair is pretty unappealing and would be right up with with "worst case" scenarios in my mind. There are just too many reports from people online, and people I have talked to, involving cases where scraping follicles during surgery did not get all the hair for me to feel comfortable taking a chance like that. For that reason I highly, highly encourage all of my trans friends considering SRS to have the full electrolysis regimen prior to surgery no matter WHAT the surgeon tells you. An additional 1-2K (and some insurances will pay now) is a small price to pay to pay for a result that you will have to live with for a lifetime. Personally I have found the process to be much less painful and unpleasant as many said it would be, though I do use LMX 5% and take Tylenol prior to my sessions.