Tax disc's can be stolen from motorcycles far too easily. Simply because it is difficult to truely secure such an item on a vehicle which is essentially open to the elements. It then costs the victim of the theft money in order to obtain a replacement and stay legal. Why bother going through the expense and hassle of printing and distributing tax discs for motorcycles at all? A receipt can be given for proof of purchase and the DVLA database used as the master record.
Abolish the requirement for motorcycles to display a tax disc. The concept of displaying a paper disc in an unsecure location in order to demonstrate legal satus is archaic. Especially considering that the relevant authorities are perfectly capable of establishing the legal status of a vehicle simply by interogating a database.