Diff lock optional on 2009 Terios?


I've been looking for a small 4x4 for light off road use. The newer model Terios ticks the boxes for me but I've noticed that some have a dash mounted diff lock button but in others I've seen there is just a blank switch.

So I get what a diff lock does. Online reviews suggest that all these models have it but clearly that isn't the case. I've recently viewed three different 2009 cars and they all had the blank switch. So are these still 4x4 but just no diff lock? Seems odd and not apparently spec related as I've seen a base spec model same year that did have the switch....

I'd appreciate any insight. Thanks.