If this practice doesn't yet exist in classical circles, I fear it won't be long before it catches on.
And nobody seems to know how to fight it
This has worried me for some time, IRF. I usually try to buy tickets in person from the box office if at all possible as I simply can't see any justification for any charges other than recouping expenses over and above basic operating costs. In other words, it is part of the seller's responsibility to provide basic availability free of charge (or included in the ticket price whichever way you want to put it). If, as you say, you want the convenience of having the ticket posted to you it's reasonable that you should pay for the stationery and postage, but the actual issue of the ticket is not, in my opinion, something that can reasonably be regarded as an ancillary service - it has to be done anyway so what are they charging for?
You are right in your observation that this kind of thing is less prevalent in 'classical' circles but even there you can find some very annoying tendencies. Now that the four-year Ring cycle is over I shan't be booking any Proms in advance this year. They charge about £5 for the brochure containing the booking form but when you fill out the form they charge another £2.50 (?) just for
using the form you've already paid for! They then allocate the seats
they select for you and issue non-refundable tickets. By not booking ahead I'll save far more than the £7.50 brochure/booking costs because I won't be lumbered with tickets for Proms I can't attend and have to give them away (this always happens when I book in advance); and I'll be able to choose my own seat from the (often huge) range left after advance booking rather than just telling them my preferred price band and accepting what they give me.
The Liverpool Philharmonic Hall charges an extra fee
per ticket just for booking on line and, if my experience of doing this for the Wayne Shorter gig is any guide, issues 'best available' on the basis of what's best for them rather than for the customer. I simply don't book in advance any more and, judging by the surprisingly large numbers of empty seats for names as big as Shorter and Ian Bostridge, I'm not the only one with this policy. I might go there on April 5th, though, to hear the Durham concerto you recommended - that depends on whether there are tickets left and whether I feel able to sit through the Michael Nyman piece that opens the concert!
I don't know how we can fight this tendency. I suppose the OFT is the first port of call but it seems to me this trend is of a piece with the way we have all been forced to have bank accounts/credit cards and use direct debit and the OFT hasn't helped there. I bet if you complain to the venues or the agencies you'll be told the customer has
chosen to use these services. But like bank accounts, credit cards and DD payments this is, at least for pop/rock concerts, pretty much Hobson's choice.
There is one venue I know where even if you walk in yourself and buy the tickets in person, they charge you 25% for the "convenience"
That reminds me of the system in place for most venues in Germany (and Belgium?) where you actually get charged extra for the privilege of booking in advance. If you wait until the day of the performance you don't pay the advance booking fee and quite often you can benefit from various 'last-minute' and 'standby' offers. To be fair, though, the fee isn't very large and the ticket often entitles you to free public transport from several hours before the gig until the next morning (a very worthwhile concession in my experience).