Several basic questions about alternating voltage / current
For a transmission line to behave as a transmission line, the wavelength of the (AC) signal needs to be smaller than the length of the transmission line. This is because the "wave" should "fit" inside the transmission line.

wavelength = speed_of_light / frequency

So take for example a 2.5 GHz WiFi signal, then the wavelength is \$3*10^8/2.5 * 10^9 = 0.12\$ = 12 cm

This means that a short (coax) cable designed for 2.5 GHz signals will behave as a transmission line.

But for the 50 (or 60) Hz mains frequency the wavelength is 6000 (or 5000) km ! That means that the transmission line way of thinking does not apply here, the cables are simply too short (compared to the wavelength). This means that the mains cables can be treated as a "direct connection" perhaps with some series resistance. But there's no "wave propagation" going on like in a transmission line, at least not in the sense that we need to consider and account for that wave propagation.