For a new iPhone user are there alternatives to using iMessage for texts to avoid this?
Signal is a good recommendation, but you won’t be able to convince 100% of people you need to interact with over text to use Signal. You might convince friends and family, but not acquaintances or random people who might need to text with (like your electrician etc.)
Given the tradeoffs, iMessage is pretty good for day-to-day messaging.
I'm outside the US, so I don't even need to consider. Nobody here uses iMessage, even the people with iPhones.
What? How-so? I've never allowed it to do that and it works fine for me, across iOS/Mac/Windows.