Usually MDF is used if you want a high gloss smooth finish as it doesn't have any grain.
Don't be too hung up on "solid wood" as it's just two thin pieces of plywood on either side with some filler in the middle for support.

Each material has its pros and cons. My current kitchen and wardrobe is using "solid wood" and finished with exotic wood veneer. I had it for 6 years. Trust me, it has it's own set of problems.

Maybe I said it wrongly in my previous post. Some are indeed real solid wood. When I say solid wood, I mean the whole piece from top to bottom is from one solid piece.
Usually they are Nyatoh wood.

I am not sure what you mean by laminates but to me its the part that you see and touch. Laminates is some man made material and veneer is a piece of thin "skin" from a real tree.
The laminate or veneer would go on the plywood which gives you the final finished look.

You got to remember that a complete cabinet has several parts (carcass, doors, shelves) and they could be made from different materials.
When they say solid Nyatoh, do they mean just the doors? You got to ask about the carcass and shelves

Did you say they use mdf for their carcass?

You means Signature Kitchen?