I also look at someone like Mort though.
Really damn powerful now, but he has a cell phone. I'm sure some of that is that his power isn't coming directly from himself, so there's less conflict and thus less static.
But that can't be all of it. Control seems to be a very important aspect too.
The idea of "Yeah, you can use technology, but it will never be durable and you'll never be on the cutting edge." So you settle for cheaper prepaid phones because you know they're going to fizzle. It's just a question of when. You don't bother with a computer and try to use an old tv for as long as you can. You prioritize wired connections over wireless because you're less likely to interfere.
Harry's a terrible example. He's the pot that's always boiling over a bit. He's also broke as hell. A wizard with resources could buy technology that's relatively cheap, never be an "early adopter," and set up controlled environments where he can use technology if he's very calm or specially prepares himself. Like, for instance, cutting himself off completely from his magic.
It's a matter of investment. Harry was raised old school, then out in the Ozarks. Magic was something special that he hid from others under Justin. Then he was raised in the middle of nowhere with an old guy who's crazy powerful. Technology was never something he valued, so he never saw the point of working really hard to have it. He also never had the money to waste trying. Pile that on top of "I've got very little control over myself" and there's no way he would have access to all of it.
But Molly probably could have learned to work around it and have a more normal life.
Until Harry died and she went off the deep end.
Mort's life seems more normal, in regards to technology, than Harry's. Maybe Ramirez's is too? Or some of the other younger wizards?
Granted, none of this should completely remove Hexing. The wizard's lab is probably hell on technology (I'd set up very strong protections to contain any magic there). Anytime you're actively casting, especially evocation, then all hell'll break loose. But if you live a quite life, maybe not so much?