Quite often used in model railroading, particularly with DCC decoder installation. In many case, the original system was designed to transfer power from the wheels to the motor as cheaply as possible - this usually involved rubbing metal contact surfaces. For DCC decoders, the motor (brushes) MUST be isolated from the wheels, it's a 4 wire system (2 in, 2 out) and never must the output be allowed to contact the input or the magic smoke is quickly released. Kapton tape is preferred since it is thinner (keeps the motor better aligned with the rest of the mechanicals, and space is often at a premium - a mm here or there can be the difference between the body shell fitting back on or not), stronger (resists wearing through), and also far less messy than black electrical tape, which leaves a gooey mess everywhere. I bought a roll some number of years ago and it's probably more than I'll need in a lifetime, but it's there and available whenever I need it.