The Business Model That Makes Restrictions Inevitable
Retail bookmakers are not in the business of taking on all comers at market price. They operate a margin-based model: every market they post has a built-in overround that, applied across a large recreational customer base, produces predictable profit regardless of race outcomes. The mathematical edge belongs to the book.
Sharp bettors break this model. A bettor who consistently identifies lines that are too generous forces the bookmaker to either accept losses or refuse the action. For a mass-market operator, the commercial decision is straightforward: restrict or close the sharp account and preserve the margin from the recreational majority.
This is why the restriction problem is structural, not personal. It has nothing to do with "fairness" and everything to do with bookmaker business design. The same bettor who gets a £20 stake cap at a retail book might be welcomed by an exchange because exchanges profit from volume and commission, not from bettor losses.