The entire Premiership, Football League, Conference and their fans have just observed a minute silence after a 6 minute delay to kick off.
I don't think it's necessarily the same as the solidarity shown by the clubs mentioned. A minutes silence is, to respect the dead, which is great and no level headed person wouldn't be against that, but doesn't really get behind the campaign in the same way as some of the clubs mentioned have.
I'd say that honestly, it's because fans of those clubs don't have anywhere near the level of exposure to the issue as those of English clubs do - doesn't matter how bad the tragedy was, what happened or who said what about it, it's guaranteed to eventually get to the point where a person is fed up of hearing about it.