I don't see this.
Some cameras are really good at certain things while some just blow up the competition and set themselves apart.
Yes, but then you pay for the difference
Perfect example is the Canon HF100 which was an amazing 1080p camera.
Then came the Canon 5Dmarkii that revolutionized the industry for amateur video.
Yes, but I assume without looking things up right now, the Canon HF is a dedicated video camera? With a fixed optical and digital zoom? So you pay a certain price for it.
The Canon 5DMK2 being a DSLR you pay for the body, then throw on whatever lens you can afford and your optical zoom becomes a variable, the variable being, whatever lens you slap on it.
Lens prices vary, obviously. So a fixed 12 optical dedicate video camera at $1500-$2500 versus a camera body that itself alone costs $2500 + your lens $$$ = a lot more.
The OP was talking about a "camera" so leaving video out of this, brands don't matter, at this point these days, it seems like a lot of cameras are on par in terms of noise levels, low light, etc.

