I think its all a question of the perspective and where you're from and what you earn. I'm from a small german town and compared to the prices for a meal here DLRP is expensive! And it depends on what one want to eat and what one is expecting for that price. Some prices are more or less comparable with german prices others not, some are ridiculous.
I couldn't imagine what your main dishes prices are in the UK compared to the ones in DLRP but here are some data from Germany.
I think for example a Schnitzel might be very "exotic" in Paris because one can have one with french fries and vegetables in Germany for about 10-12 euros (and not only in my small town) and it costs in the KIng Ludwig's Castle about 18,50.

If they wouldn't have pigs or veals in France, i think not even the import costs for ready-made Schnitzel really wouldn't exculpate that high price. I really think one pay for the name Schnitzel then. It sounds foreign and so its expensive.
Or for example mexican food. In Germany one pay about 8-12 euro (depends on the town/city) for a burrito or fajitas. For the Fajitas one pay in Anettes Diner 19,50!

Something that is really o.k. are Pizzas: 6-9 Euro in Germany 7-8 in Colonel Hathi's Pizza Outpost.
But it is also a psychological thing. Since we have the euro in Germany and France everything is much easier to compare. As there was no euro i said to myself: You're now in France in a foreign country, with a foreign currency and foreign prices. Eveything was o.k.! Now one better recognize what one pay for and sometimes the quality of the food (especially fast food) does not exculpate the high prices. And that's what's sometimes annoying.
Because most of you on that board are from the UK and you calculate with pound sterling - so the psychological thing is not a problem for you, is it?
The huge
but: I know I'm in a amusement park, in that amusement park par excellence. In Paris. One of the worlds famoust European cities. And so the prices are indeed sometimes annoying, but one may reckon that it is expensive. And so I do (though i'm sometimes annoyed)! And I'm glad that the magic there makes amends! And it does. For me!!
And if you don't want to drive far away to eat, you have to grin and bear it (IMO)!