Chicken Enchilada Volumetric-ky Difference-all Equations

I have different levels of competency for the variety of fields in mathematics. One that I don't understand is 'Chicken Enchilada Mathematics'.

A local restaurant charges $5.29 for one CE with chips, hot sauce, beans and rice. Plus a very tiny amount of lettuce, let's not really call it a salad. Add a 2nd enchilada for $1.40, add a 3rd for $1.00 more, BUT a 4th enchilada costs an ADDitional $3.28 (?!?!?)

Please bear in mind that nothing else changes as they add more CE. The amount of beans, rice, chips, ice water, napkins, forks, spoons, fluorescent lighting and air all stay the same. I am just trying to have a little more to take home to my dog for his evening meal.

I even clarified the ticket with two people just to be sure they were charging the "correct amount".

My wife asked me, "we aren't going to stop going there just because of this, are we -(?!?!?)- You can find something else to feed Cooper." She likes the less crowded atmosphere versus other places in town. I told her that we would continue to go there because I love their hot sauce. But the 3 enchilada meal at the more quote "expensive" unquote previous restaurant probably has a greater volume of food than the escalated exponentially inflationary 1-2-3-4 CE meal which I'm sure is now more expensive, for essentially the same quality & ingredients meal. Again, hot sauce quality is the crucial deciding factor.

Oh my, I just heard someone on teleBision turn 'fajita' into a VERB with

" ... just fajita-erize 'em ... "

translated as

'to cut meat into fajita size and shaped portions'

Thanks Emeril L. for the chuck L.