Definitely NOT too good to be true.
When I got my Doctor (MD) letter in England I was already living full-time female and had medical proof (lab tests) that I had already been on medical-grade hormones estrogen, spiro, and progesterone for quite some time already.
I started my transition to womanhood in a developing country where prescriptions are not required to get medical-grade hormones as they are in English-speaking countries.
The doctor had loads of questions, but since I was presenting myself to him with very female voice and pitch, female face, great skin, genuine small B-cup boobies, and totally feminine mannerisms, it would have been pretty difficult for him to deny that I am female.
Yeah, I was successful in getting my British Doctor's Letter in just one visit. The cost was 100 pounds = about $140 US dollars.
So, sure, in the right circumstances it is possible.
Please note also that I got the in-person referral from a British trans female friend who told me the Clinic name in London England when I met with her face-to-face about a month before my Doctor's appointment. I implicitly trusted her advice, and her recommendation was simply super of which Gender Clinic to go to.
Hugs,
Jennifer xx