I happened to be buying tickets from Maidenhead to Marlow today and they were still firmly ‘paper only’.
As a related point I was quite surprised to find that with a decent sized festival taking place at Marlow today (Tom Kerridge’s Pub in the Park) and with the organisers advising attendees not to drive and to take GWR▸ (Great Western Railway), that a 2-car turbo once per hour was expected to convey everyone back to the mainline. Is there no capacity to enhance that service for events, be that length or frequency?