The text of Mr Brannan's letter in the Courier can be found at:
http://www.thecourier.co.uk/opinion/readers-letters/let-wealthy-pay-for-st-andrews-transport-1.913844
We must assume that Mr Brannan's suggestion is a serious one. Doubtless it will be one of the options that the STAG evaluation will consider. However such a scheme would lose all the advantages of through-running and so would not maximise usage. It would in effect simply be a more elaborate version of a bus, with the same physical gap between train and tram, unless the proposal is for the tram to run across the railway line to the platform. While doubtless this could be done, it would most likely significantly increase the cost and for little return, whether for the public purse or a private operator. It is interesting that Mr Brannan objects to public money being used specifically for a railway; I wonder if he also thinks that road improvements should be funded by private funds?