are these systems only used in southern states where winters are mild
I live in Illinois and can have cold winters

What is 912-0090? Is it a phone number and what is an "outdoor sewage system". I have no idea what you are asking.

[www.plumbingsupply.com]

it appears that this is a sewer ejector with the discharge exiting the side of the tank rather than the thru the cover.
i've never seen one up here in new england but i would imagine that the tank will not freeze but the discharge may freeze because it is a pipe full of water that is held back by the check valve.
i'm guessing about the tank not freezing but then it just might..
in any case, i would not want to be called to service the unit if it sits in the ground outside and the temperature is close to zero with a 30 MPH wind..

The Zoeller outdoor sewage pump systems are normally used where ground elevations make it impossible for normal gravity flow drains to be installed. Some ground conditions will even cause the septic tank to be installed above the house elevation making gravity drains impractical, and the best solution is a sewage pump system

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

thinking maybe heat trace from tank to check valve and plug in for winter its less than 6 feet to tank

Even here, without basements in most homes, the outdoor pumps can be very deep, making servicing them a challenge. For that reason, most are installed inside the building.

the tanks that come with this system are 30 inches deep and I wonder if heat trace from tank to check valve would be a possibility for winter months

They may be 30" deep, but outdoors, most of them need "extensions" to raise the cover to ground level.