They can quote the laws verbatim and understand them extremely well, but they don't have the time to understand you or your situation.
For many with normal lives this is probably fine (9-5 job, an ISA, pension etc...), but when you have levels of life complexity that lie outside of this, the tax advisors frequently jump to wrong assumptions and therefore wrong conclusions.
The same thing is happening to my relocation agent, he has no idea how to understand my life and my expectations, because nothing he's encountered before has any resemblance to me or my life.
Self sovereignty is both a blessing and a curse ๐