OK. I've missed a whole chunk here, but I'm back with my theatre tokens.
First, I did exchange them pound for pound, so I'm not a 'skank' according to someone's (can't remember who) definition. £20 theatre tokens for £20 ticket, roughly.
Now I've got that out of the way...
Suppose instead of taking my tokens to the theatre, I took them to Tesco to spend there. Do you know how much they would have been worth? Nothing. Zilch. So clearly the value of my tokens is zero so I am a much bigger skank than the amusement mark woman as I should have charged my friend nothing at all.
Basically, there is no 'true' value of vouchers, tesco points etc. It depends on the "opportunity cost" for each person. If this woman would have used for points for another themepark then the opportunity cost/value is £25. If she would have used them in Tesco it is £6.25. But most of you say that you don't use them in Tesco, so probably £25 is right and this woman did nothing wrong.
And if I hadn't used the theatre tokens now I would use them later, so the value is £25. But not if they were about to expire.
Having said all that, if I was just buying the ticket for one friend with my voucher I would probably have mentioned it (but been very surprised if she thought she should have it for free). Because I was buying tickets for five of us and only had two tickets worth of vouchers I didn't bother mentioning it.