We tried that in the US. The incumbents did weaselly things to make life difficult for the CLECs, and eventually lobbied Congress to remove the requirement.
LLU is essentially irrelevant today, it's fascinating that people keep bringing this up.
LLU happens at the exchange where the local loop edge is. But today's users want speeds which aren't practical over the long local loop. So the fibre was pushed out to street cabinets, FTTC, which are much closer to the end user and too small and numerous for LLU to work.
This makes good technical/engineering sense but it means there is no real competition. What the UK did about that is heavy regulation. The regulator decides how much can be charged to deliver the FTTC service from a consumer to a POP owned by an ISP as a wholesale price.
But most Subs don't want to pay the premium for FTC a lot of the high profile whining is from business's who think consumer BB is appropriate fr a business and want residential customers like pensioners and /or bt share holders to subsidize them.
when I helped sort out our BB for an office move in Farringdon (London) there is a lot of whining about BB but we manged to get a 70Mbs ELM in less than 2 weeks and 100Mbs in a quoted 3 months actually delivered less than 2