I think it's because of outside of their fan base the gp doesn't really use them.. all their fans buy their songs at once then couple weeks later no one is buying it? I'm not quite sure so don't argue with me if I'm wrong lol
Some of their singles have had bad timing (i.e. Best Song Ever - going up against Blurred Lines, Drag Me Down - not releasing the video alongside with the song). Another problem is that a lot of their support comes directly from their fanbase, so their sales don't always align with their airplay when it hits its maximum.
Honestly their songs rarely stand out to receive substantial airplay/streaming and become hits. They've had two real hits in the US: Story of My Life and What Makes Me Beautiful. Maybe their label aren't pushing them enough on radio (besides these 2 songs)?
