Because it doesn't work like you're thinking it does.
A 27" IPS monitor may not have a significantly greater material cost than a 32" IPS TV of similar capability, but when that 32" TV is expected to sell 20x as many units, component costs can be reduced greatly through economy of scale.
I get that. I guess I just thought that competitive forces would negate it to some extend given that the monitor market must be pretty big in itself and true production cost would not have such a great disparity.
but then that doesn't stop most car manufacturers selling their 10% larger cars at nearly twice the price!
production cost and sales value are far from linked!