Both of the women I hired encouraged me to contact them by phone or email or text. I don't text all that much in general but I don't see texting a therapist as any different than any other professional. The reason I would not text a therapist is that I don't want those people intruding on me. I don't see that texts have to be responded to any more than I feel I have to answer the phone if it rings or that I have to respond to an email. The sense of urgency on the part of a sender is on them -not me.
I never concerned myself about what was or was not fair to a therapist. Those people can take care of themselves. Fairness doesn't enter into it as far as I believe.