I would say “U2 are a great band” but lots of people on this messageboard would say/write “U2 is a great band”.
That’s all I’ve got…
In general, in the US, collective names are singular and in the UK, they’re plural.
No wonder the Irish get confused. 
Yeah we’re half way between. I think from now on I’ll say “U2 arse a great band”.
Unless the name itself is a plural: “The Beatles are…”
It seems the singular is the most used by far, at least on the internet:
google results for:
“U2 is the band”= 20,000 results
“U2 are the band” = 5(!?) results
This is absolutely shocking, considering:
“U2 is a band” = 13000 results
“U2 are a band” = 4,000 results
what is the explanation for this?
Bullshit. I bet most people on this MB would say/write “U2 hasn’t been a great band for decades.” 
Lots of American U2 fans?
Well U2 is/are isn’t a great example. Everyone knows they are a band. Would likely be better to search “Deep Purple is a band”/ “Deep Purple are a band” or something like that.
Deep purple are a colour.
I haven’t anything to contribute, but I just wanted to post in this thread before it turns nasty. It will turn nasty.
I was more surprised at the difference between results for
a) “U2 is THE band” vs. b) “U2 are THE band”
here, a has 4000 times as many results as b
and
a) “U2 is A band” vs. b) “U2 are A band”
where a has just THREE times the results of b
(no uneven sample sizes either, “the band” and “a band” searches both totalled around 20,000 results)
Im just wondering why the difference between “the band” and “a band” changes the likelyhood of “are” being used by more than a thousand times