SCART is used in the UK, Europe and parts of Australia etc.
Its basically a 21 pin connector which provides lots of AV functionality in the one connector. So you get RGB, Composite Video, Stereo Audio etc.
An arcade monitor uses RGB, all televisions use RGB, the cathode ray tube in a TV fires electrons at the phosphor coated screen and the combination of Red, Green and Blue determines the colour of the pixel on the screen.
An arcade PCB directly outputs RGB video, so that just goes straight to the monitor. SCART is not used.
However you can wire up a PCB to a SCART plug and use on a television with a SCART socket.
In the US you won't find televisions with SCART sockets as for some reason they decided composite and s-video were good enough.
You can find an old Commodore monitor that has analogue RGB via a 9 pin D socket, or perhaps a round DIN connector. Then its a case of wiring up a custom cable from the arcade PCB to Commodore monitor.. or find an imported television..