"Assuming" is doing a huge amount of heavy lifting, right there: pretty much everyone I know, as an example, who has their own business has their partner as a director (even if they spend all of their time shopping, golfing, or in the hairdressers), and their RRs and Porsches "through the company"............
SO, your back-of-a-fag-packet sums are likely way out, before you even start.
Bother with what? Your point is not at all clear.
Just saying it is a "fact" doesn't make it so.
A basic rate payer has little-to-no opportunity to reduce their tax obligation.
Someone on £300k has a lot of avenues to do so; you acknowledge this yourself, in the same paragraph:
Which is all perfectly legal.
And, all of your points are moot anyway, as the title of the thread was about fair tax.
The people you're advocating for are the same people you have repeatedly said will sling their hook if they don't like it.
And yet, they're still here...........