Voice is a HUGE tell and the best part of all is that it is very low cost.
A personal voice trainer is a great option, but there are also some very good voice programs out there.
A good friend may even be able to help out. Listen to how they speak enough and you will start to mimc it. I say that because even before I accepted transitioning 80%+ of the time I got ma'am on the phone or drive-throughs without cameras. The reason is that I picked up my phone "voice" and "mannerisms" from my (grand)mother when she tried to teach me proper phone etiquette.
Now my in person voice....... I am still working on it (or other tells are getting in the way). My voice didn't drop hugely in puberty. I gained the ability to make it drop, but it stayed pretty much the same. I used to get double takes when co-workers or corporate partners would meet me in person after a few phone calls (our company is mostly virtual/remote), because my voice didn't match my big size.
I also used to consistently have nasal congestion issues, but I'm hoping that now my septum has been repaired it may get better so that should help some too (congestion gives you a throatier sound I think).
There are a huge laundry list of things we can do to help pass better, and many of them are free/low cost. Even better most of them can be done in parallel. We all pick and choose as many of the paths as we can at any moment and then go back and hit the others. Why are you so anti-FFS? It is just another tool in the box. You can still use all the others (and should). This isn't a desert island situation where you only get to pick one.
Could I not take your question and phrase it this way and it still be valid?
"I'm still shocked at how many MTF will spend $20,000+ on GCS but refuse to deal with their voice."
Doesn't that show that this is really about FFS and not really why aren't we doing voice. Yes there are people that don't need it. Yes there are people who go too far. But NO not everyone can get by without it and some people do need the works. It is a very drastic procedure and yes it is very expensive too. That is why it needs to be carefully considered by the person choosing it. It is all about make sure you are truly certain and weighing out the balances in your mind. Once a person has made that decision then it is right for them.