I question your use of the word typically. I do not believe utilities typicality pay for the cost of the sewer lines or a homeowner hooking up to the sewer system. In my experience (albeit in Michigan), the costs are borne by the homeowner, whether hook up is mandatory or not.
Homeowners are assessed for the line according to frontage and then pay to hook into the line according to distance from sewer line to home. Therefore, the closer a home is to the sewer line, the less costly it is for a homeowner to hook into the line.
Again in Michigan, block grants are available to homeowners and a lien will be placed on the home for cost recovery when the house is either refinanced or sold.
Again in Michigan, the work on the lines is contracted out.
I know that Michigan is not Texas. I also know that North Carolina is not Texas. I would be cautious about using words like typically unless you know what is typical in Texas.
Well I feel comfortably saying "typically" based on my experience working on projects for approximately 60-80 public utility entities in 5 different states, though none in Texas. And "typically" by no means is an absolute proclamation, it just means more often than not. Additionally, information I've ascertained through my membership in professional organizations that share information from public utilities across the country is also a source for which I base that belief on.
I understand your point and logic, the homeowner typically IS responsible for absorbing the cost of installation of the sewer LATERAL and clean-outs (including future maintenance/repair) within their property boundary but do you think the linear distance between the house and side/rear property boundary is going to be significantly less than house and roadway and lead to some kind of huge cost savings? Also, depending on the slope of the sewer and the property, it's possible that you could have a sewer main running through a property but your sewer lateral may have to be connected to the sewer main in the right of way.
The more common practice from my experience is that public utilities will pay for costs to install sewer mains to provide service to property owners if they're servicing an area and they typically charge a fixed tap/impact fee based on service type. Note that a "tap fee" is intended to cover cost of materials/labors for the connection AND future impact to the sewer system, hence the reason why it's typically a fixed fee in many municipalities. Now for properties that are not being serviced by a public sewer entity, they can request that service be extended to their property and in cases which utilities are willing to do so, there likely would be additional costs incurred or cost sharing. But back to the original point of debate, I don't believe there's an inherent cost saving as assumed in having a sewer main running through the property.