It all depends upon your definiton. A transformer coupling can be designed to withstand kV of common mode voltage on the balanced side. This cannot be done with semiconductor circuits.
I was thinking of the common case of sending audio signals over long cables and having transformers at the ends.
If you have small common mode voltages, the classical op amp circuit with four resistors will work. If you use 0.1% resistors the CMRR should be near 55 dB which is pushing the op amp limits. You can also use the classical three amp circuit and get 75 dB or more.
telephone line needs handle more then 1500 Volt differences between modem-side and phone side for resist high voltage depend of stroke of lighting etc. but also to resist big voltage differensen between houses locale earth and phone station local earth voltage , is easly more than 15 - 30 Volt and very noisy...
Is ok using electronic balance on short distanse in same buildings power and grounding branch, but between houses you need galvanic isolation if not want (big and sporadic) problem.
10 base-2, 10 base-T and 100 base-T network equipment using uses isolation transformer to cable even for short distance (small black boxes on every network card)