I was walking in the Hudson Bay department store the other day and did a little double take in my head. This only because the woman working behind the counter I had just passed suddenly got on the phone and a distinctly male voice was coming out of her. She had clearly transitioned and I would never have guessed she was trans as evidenced by her appearance which was of a middle age petite well dressed woman. I also surmised she had transitioned quite some time ago.Unfortunately, voice does matter if not having people question your gender matters to you. Not all trans people feel this way of course, while others resort to speech therapy or even surgery to increase their ability to blend in. There is no right answer.
Voice did matter to me and I worked on it until I achieved a voice that always worked even on the phone. It took a few months of daily practice but it paid off in spades. There are plenty of YouTube videos that explain the technique and just to put things into perspective for you my natural singing voice is a baritone so it can be done because I never get double takes when I speak.