If it is accessible enough for you then it is accessible.
As a generalisation about compliance (or conformity!
) with regs, that simply is not true. There are umpteen aspects of my electrical installation which are 'acceptable enough/safe enough for me', but which either are, or might be argued to be, non-conformant with regs, so I would not normally talk about them here, or advise others to 'do as I do'.
Interestingly, given today's date, and your recent reminder of the new definition of "non-compliance" which we believe will have been published today, many of the things I am talking about (which are 'acceptable enough/safe enough for me') could well be examples of things which are non-conformant with regs but could be argued to
not be "non-complaint" (per the new definition, assuming it appeared). I foresee a fair bit of discussion about this over the coming weeks and months.
Inaccessible is presumably when it is not accessible enough for you - or when someone may not even realise there is something there. If you have a sticker on your carpet on an easily lifted area stating access to junction box below, then that would be alright.
Needless to say, I have never had 'stickers on my carpet'. The existence of the junction box, and access thereto, will always have been documented elsewhere, but there has never been any 'local labelling'. Would you regard that as 'accessible'?
Kind Regards, John