> use mobile data on their smartphone, which practically never works because the subway is, well, deep under ground. I find surprising that London hasn't deplo

> use mobile data on their smartphone, which practically never works because the subway is, well, deep under ground. I find surprising that London hasn't deployed a cell network under ground like Stockholm's tunnelbana has. I'm sure there are technical differences between the systems but the tunnelbana has spotless mobile data even deep underground in the bedrock.