That's a bit of an oversimplification. Access Points coordinate communication to ensure clients take turns, and Wi-Fi avoid collisions by having clients listen

That's a bit of an oversimplification. Access Points coordinate communication to ensure clients take turns, and Wi-Fi avoid collisions by having clients listen for an idle channel before transmitting and exponentially backing off if it's busy (CSMA/CA). So even when clients share the same frequency, it’s not 'circuit-switched' since transmissions are managed dynamically. Clients wait for the AP to respond before sending additional data. And there's QoS features to ensure things like live voice take priority over a bulk download. Wi-Fi 6 adds OFDMA, which splits channels into sub-channels so multiple clients can transmit simultaneously, and MU-MIMO allows simultaneous streams to different clients. Beamforming helps too with directional signals. tl;dr; it is a shared medium but with lots of tech on top of it that mitigate much of the issues!