Quite simply, with the larger companies, the exact price fits the customers assumed worth.
Its a bit like buying double glazing but, unlike double glazing, the sensor companies rarely go so far as to advertise the starting price.
Equally the companies do not advertise the fact that they are primarily offering you a ball turret with a badge engineered content.
The only really effective control over every company having access to exactly the same cameras is for them to take over the supplier and 'corner' that particular camera option.