That's why I never buy anything from these places. Can we revolt against this? yes. But no matter how many times we revolt or complain, there's no visible change. These vendors are a source of income(profit) for the owners of these entertainment places. So, this going overprice habit will never die.
The stronger a light shines the darker are the shadows around it.
'Idhuvum Kadandhu Pogum "
Even this challenging situation would ease
Because at those places you go for recreation , entertainment and fun. You do not think much about spending few more bucks on edibles as you are in full mood of enjoyment. You think that if I will not spend my money on recreation then what is the use of this hard earned money. At those point you fail to understand how you earned those money. You forget about all the pains and struggle and only focus on relaxing yourself. As food is a important factor that can make you feel good and relaxed without bothering much you pay what vendors ask for, even it is higher than MRP.
Vendors at those place only exploit and take advantage of your fun seeking mood and price products at higher than their MRP.