The security for a utility account greater than for a bank account
I am pretty sure it's the other way around. EVERYONE has the basic utilities (it's not a third world country), but many people can't pass KYC to get a proper bank account, and we have the "basic bank account" scheme to cover these people so that government can pay their benefits direct, due to the old Giro system having been discontinued.
All a utility company worries about is getting their money for whatever is used. A bank has to worry about money laundering, as well as getting back the money it lends on overdrafts and cards.
Many people who rent pay towards a "household" set of utility bills, usually in the name of a landlord or nominated tenant. The only people guaranteed to have a utility bill in their name are those who live alone, and own (or have on mortgage) their own property.
Every adult will also receive letters from the government, but unlike bills, they are not regular. Most tend to arrive around the change of the tax year, and many would be in the name of the person involved, rather than some nominated head of household. Those quoting the national insurance number along with the name and address of the person should be the most reliable of all, although players are likely to be reluctant to send these in. The tax coding notice and P60 would be two government letters that always go to a named individual, and tie them to their national insurance number as well as street address. They are always paper documents, posted to the person in question.
Not all casinos accept the validity of PDF utility bills, yet it is government environmental policy that lies behind the shift from paper bills to internet statements, so it's only going one way as far as casino KYC is concerned. The utility companies have to meet certain targets, and face penalties for failing to do so. Switching customers to internet only billing is one way of moving towards the targets, and a carrot and stick approach is being used, with more emphasis on the stick recently (customers are now being "fined" far more than the actual production cost for refusing to ditch their paper bills, the intent of this "stick" being to drive those who resist to cave in and accept paperless billing).
The UK authorities are tending to lean heavily on businesses that get "anal" about their KYC to the extent that the average citizen has a struggle to comply. The banks have already had fires lit under their asses about this, one such fire resulting in the banks getting their fingers burned and forced into operating the government's "basic bank account" scheme in order for the policy of phasing out cash payments of benefits and pensions to go ahead.
With Tropezia OK with internet utility bills, this is something to advertise as a selling point, rather than something buried in the banking pages. There are many players who face the worry of their chosen casino giving them trouble over their internet utility bills, so knowing from the start that this would not be a problem at Tropezia should steer such players their way.