I can come to Texas, but it's not within my power to change the building codes there. (If I could, I surely WOULD though- it's a crummy way to build, and Texans deserve better!) The popularity & economy of slab-on-grade construction make attics a cheap & easy place to route HVAC ducting, but routing any part of the duct system outside the thermal & pressure envelope of the building comes with a big uptick in cooling & heating cost.
Sealed & insulated crawlspaces would be a better place to route the ducts, but it's more expensive to build that way (another set of joists, with more expensive floor.) A slightly less expensive option is a dropped service cavity below the air-sealed & insulated attic floor, which can use much smaller/cheaper framing lumber, since it's only holding up the ceilings, electrical routing, & ducts. But since few builders are familiar with how easy that can be, with no market to drive it, that's not how most homes are being built. A lot of higher performance houses are now built this way, along with housed insulated at the roof deck, making it a conditioned attic. But insulating at the roof deck typically involves more expensive insulation & air sealing.
Oil heating (both boilers & hot air) is still fairly common in the northeast, particularly in locations that are off the gas-grid, since it's cheaper per BTU than propane, and outside design temps are below where many heat pumps won't operate (or won't operate efficiently.) The heat pump solutions are getting better year on year, both on efficiency and l0w-outdoor-temp capacity, but electricity is pretty expensive in much of the region. Ductless mini-split heat pumps still beat oil for heating costs by a huge margin, even in those higher-priced electricity markets. But even dual-fuel units with propane burners as the second stage ducted heat pumps or air source heat pumps with auxiliary heating strips are substantially cheaper to heat with than an oil boiler.
In smaller houses with open floor plans adding just ONE ductless mini-split can sometimes cut the heating costs by more than half, even if they keep the oil-boiler in place as backup for when it hits negative double digits. This testimonial
video by a couple who live in Presque Isle ME (US climate zone 7, a-yuh, pretty damned cold!) put out by Efficiency Maine may be an outlier case, but it's not an extreme outlier.