I suggest that if the caterer can pay the VAT on the coffee, so can the sport horse sellers.
I know of several cases where horses are sold for exorbitant sums and no one pays tax on this.
A month ago a Maribor man sold his horse Coriano-Carhtago for a staggering 450.000 euro, not a cent of which was VAT.
Start collecting VAT from such people?