All I can say is, in the past 15+ years of SMS messaging, in the US, on every carrier, with devices ranging from the early Nokias to the latest iPhones, I have had reliability problems that are frequent enough for me to avoid SMS when possible.
I travel a lot, internationally at times. SMS just works.
Maybe it has to do with hardware and carrier. I use Verizon, or whatever cheap plan I get on a SIM card.
Samsung phone, and it gives read notifications when the other party agrees to them, and is good on fails, in that I know when one did not get sent.
When I make mistakes, I even get SMS over major flyover cities. Like I pull my phone out, and several emails and texts came through.