Texts are less important than email, and less urgent than a phone call. It’s ridiculous to think it’s rude not to reply, especially for kids who probably get 5-10 texts an hour.
If something’s important enough to you that you want a definite response eventually, send an email. If it requires immediate communication, call. Don’t apply false rules of politeness just to get a response out of your kid!
I’m reminded of the old saying: When seconds count, the police are only minutes away.
The same would hold true for any third party who isn’t physically in your presence at the time of need. You are your primary means of defense, with third parties as a backup…