Because they are an Agency and not an employer, thye can act as they wish.
Some Agencies however employ staff, in which case their only responsibility is to provide basic PPE. To get around the fact that many people could join get all the PPE and training and then go and work for someone else, they raise a charge which is refundfable on return of the clothing or is rebatable over a period of time.
PPE which is above the basic standard can be charged for.
As for training you need PTS to DO the job, not as a consequence of taking the job. There is a subtle difference.
Network Rail have absolutely NO interest in doing anything about Agencies, indeed they encourage them and use them to deflate wage costs year on year. How can NR reduce costs other than by forcing its Agency labour into cheap PPE and buy it in at rock bottom prices. Good people are walking away because there are better opportunities overseas and outside the Industry, and in any case only those who cannot get a job with a major Infrastructure Contractor would ever consider working for NR.
Network Rail are determined to remove the big Infrastructure Contractors who pay their people properly and provide good terms and conditions of employment, as well as good training and competency arrangements.
If you pay peanuts you WILL get monkeys, but then that is what NR want.
Network Rail's attitude towards it staff and major Contractors has already been the subject of a statement in Parliament however I have no wish to repeat what was said for obvious reasons. The MP who said it was absolutely correct in his summation of the situation, and it was far from flattering.