Assessment fees
Other FTOs do not charge for their assessments. You just have to get yourself there. It is not up to BA to asses your suitability for ab-initio training. It is up to the FTO to ensure that only those who show the aptitude and ability to make it through the course, are eligible to attend (and pay). This especially the case when FTO offer 'skills guarentees' to refund the money that has not yet been spent should you fail (for reasons other than putting in 110%). It is unto BA or any other airline running a scheme to see if your face fits after the FTO has recommended you for training.