Pitch charges

I have caravanned for 10 years and my little van uses electricity only for the fridge, lighting, tv etc.  I do not have an oven, air conditioning, hot water etc and yet the price I pay for a pitch is the same as the larger vans with all mod cons.  On a recent holiday I was amused by a fifth wheel (absolutely HUGE) being replaced once it had left, by a little campervan;  presumably paying the same pitch fee.  Is there a case for charging extra for electricity usage for the vans with high electricity demand?