Lane discipline

My recent trip back to the UK highlighted another foible of the British sensibilities when driving - terrible lane discipline. Technically, you're not allowed to overtake on the inside, but the problem is that people sit in the middle lane even when the inside lane is empty. By doing this, they reduce the carrying capacity of the motorway in that area to 30% or less as everyone queues up behind them trying to get into the outside lane to go past. It was like this up until 2001 when I left the UK and it's been like this every time I go back. At least here in America we're able to overtake on both sides without fear of recrimination. I don't know why that option has never been allowed in England - it would solve the irritation created by centre lane owner-occupiers for good.