You can't compare Lovefilm's £10p/m charge with Netflix's £6 as they are for different things.
The only true comparison is between both of their streaming services, which are the same price at £6p/m.
The £10 for Lovefilm includes Blueray/DVD rentals combined with the free streaming.
DVD rental is a different kettle of fish as regards to rights than streaming rights.
Having a combined service of DVD and streaming allows Lovefilm to offer both new and older titles is a good way of doing things as an option to Sky movies; I used to do it myself.
Although Netflix offer a DVD service in the US, they don't offer that in the UK.
The new service from Play.com owners,
https://uk.wuaki.tv/ offers both a subscription streaming service with the added option to buy or rent current titles for an additional one-off charge. This is a nice option, though the prices seem high to me for the one-off rentals and the subscription TV titles aren't that many. Still, good to have options. I think at one time Lovefilm had optional titles that you could pay extra for to stream, but not sure if they do now?