I've never been able to fully comprehend the practice of installing bath taps in such a way that once installed, it's a true PIA to remove/replace the whole tap assembly; let alone renew any compression fixings thereon. Why not instal taps on the outer edge/side of the tub where they can be easily accessed? And similarly taps which poke out of the wall (feed pipes etc. concealed) behind invariably tiled finish. In commercial bathrooms (hotels etc.) they usually include an access panel on the other side of the wall where possible, or create some kind of relatively easy access from the bathroom wall itself above the the taps - if not installed as in my earlier suggestion.
Some while back I bought this kit to remove taps covers which were well and truly "stuck" on; and likewise the actual tap body inside. The kit works well; but one has to be patient etc. and take one's time.
https://abdtools.co.uk/Easy-TapSplitter
I seem to recall that the chap who came up with kit was successful in getting some support from the Dragon's Den.
And if/when replacing inaccessible taps... a) why not use flexible pipe connections to them; and b) include (good quality - not el cheapo) isolating valves for each tap.