The don't really sound like the JAMC. Here are the reason I see for the comparison
A. Both bands are from Scotland
B. James Allan says the JAMC are a major influence and the most important band to come out of Sctoland
C. Alan Mcgee is promoting them and he got the MAry Chain their first single and managed them - he spread the word about Glasvegas by getting them on his show.
D. The songs are 3-5 chords - usually I-IV-V - in both bands - with a droning guitar line hanging on one note throughout
E. Both drummers on the first release played simple beats usually a lot of tom drums.
So there you go - a lot of it has to do with the situation more than the music - but people often like bands based on things like that rather than the actual music -
I liked them before finding any of this out - but after the fact it figures.