Thanks for the enlightening write-up, this does clarify things.
www.gsmarena.com
This is just speculation but I'm guessing the auto-connect delay is due to some kind of verification or authentication 'handshake' where those tablets are then involved in an exchange between each tablet with the main airMAX BaseStation in your office facility. Kind of reminds me of the annoyingly long time it takes to cold start a modem with a lot of today's ISPs.
Given your drivers could connect instantly by manually selecting the necessary WiFi network, why is this not possible with these Samsung tablets?