Phone masts the length of the train line

I write this from the comfort of the 7AM Sheffield to London train. The journey has been an “offline Google Docs” only affair. Occasionally I get really fast mobile data and can attempt to quickly catchup with emails but communication with the outside world is limited. My understanding is that this is not a technological problem but one of market incentives.¹ Network providers are incentivised by UKG to install phone masts based on where people live. Changing these rules to cover major commuter routes could be a quick and cheap upgrade to the UK rail network.