A 'three tonne lorry,' is in fact a van. Lorries, these days start at 7.5 tonnes. Two axle rigid lorries can gross up to 18 tonnes with four axle artics typically 32 tonnes and six axle artics 44 tonnes.
Yes they do drive around London at these weights.
I'm giving those who care to read, a heads up regarding safety around these vehicles. I'm certainly not the best driver in the world, but I take my profession seriously. If people choose to bury their heads in the sand and ignore sensible advice, that's their choice.
Saying 'it should be the drivers responsibility' won't do you any good when you are the one laying squashed in the road. Will it?
For once, listen to the other side and take some notice, because as you point out, there plenty of drivers of there who don't try and drive the right way.