There may be a difference between OTC hearing aid failure rates based upon those who raised in cold climates vs those raised in warm climates. This is something my AuD taught me. When she examined my ears she said I must have grown up in cold weather, which was correct. I live in FL currently. Apparently our ear canals can adapt when raised in cold climates vs warm climates. Chances are if you were raised in warm climates your ear canals are mostly straight. My ear canal has almost a 90° hook and is far from straight. This helps to protect the inner ear in cold climates and many develop a "bend" after chronic cold weather exposure as a child.
That said, "reciever in ear" silicone cones have not worked well at all for me. They just won't seat or position properly and are quite uncomfortable, even painful. The only solution for "reciever in ear" type hearing aids in my case are "custom molds". I suspect that had I tried OTC hearing aids I would have never learned about my northern type ear anatomy and no OTC hearing aid would have been comfortable or have worked in my case.