It is important to recognise that although it cannot cover every scenario, the EHRC has provided key explanations and worked examples, also based on wide consultation, that every organisation can take and apply in its own context with common sense. If a service provider is not sure, it can and should take legal advice.
It's interesting to contrast the obligations in the context of disability discrimination, and those based on transgender discrimination.
In the context of disability, only 'reasonable' adjustments are required. The meaning of 'reasonable' includes cost, effect on other people, resources available, practicality, etc.
In other words, it is accepted that there will be circumstances where that it neither practical nor affordable to make certain adjustments for, for instance, a wheelchair user, and therefore is not 'reasonable' and not required.
Other adjustments must be made, but the law accepts that there are limits.
Contrast that with what seems to have become the norm to avoid discrimination against transpeople: transpeople 'must not be left without provision', and that is interpreted as either access to whatever toilet/changing room they choose, the provision of extra 'fourth spaces' or, as seems to be happening a lot, complete removal of single-sex provision and replacing it with all-mixed-sex individual lockable 'universal' toilets.
No weighing up of the cost, the disruption, available resources, the negative effects on other users, the practicality - in other words, the reasonableness of the adjustments to existing toilet provision, which is perfectly adequate for the huge majority of the population.
I don't understand why adjustments which are actually physically needed by people with disabilities may be subjected to a 'reasonableness' test, whereas adjustments which are not needed but simply 'preferred' by transpeople have to be provided, with no reasonableness test.
In reality no transperson is 'left with no provision', as long as there is a men's, women's, and accessible toilet. The provision is there, they are not physically unable to use it, but they choose not to use it.
And on that basis, existing toilet provision can be removed and replaced by an inferior, unsafe, inadequate, unpopular alternative in order to cater for a tiny percentage of the population, without any consideration of whether or not these adjustments are 'reasonable'.
IANAL, and I can't understand - why is there a 'reasonableness' test for adjustments on the basis of disability discrimination, but none on the basis of transgender discrimination?