This seems to be universal in Australia. Even the mega store self serve integrated systems have a separate machine mounted on for processing card payments.
And even if you can hotswap a POS system, they're still expensive. A machine plus software is about $4000 per lane, and that's when you're not a captive market. Even small retailers typically have enough lanes that this is a significant expense. People in this thread are giving prices for Square readers which 1) are not at all sufficient for most businesses and 2) are sold at a loss while Square makes its money on transaction fees and subscription services (the same is true for the rest of the Square clones). It's like comparing a home projector to a movie theater projector.