Not all the towers along a transmission line are identical. Look closely at a tower where the line makes a sharp turn and you will likely find it is wider and beefier than other towers along the route. The added strength and weight are needed to resist the unbalanced pull of the conductors, which might overturn an ordinary tower. These special towers are called deviation or angle towers.
The transmission-line tower everybody knows is an Erector Set latticework of steel girders and diagonal braces. The techniques for designing and building these towers are the same ones used in constructing steel bridge trusses or crane booms. The individual pieces can be made cheaply from rolled steel and then bolted together on the site. This last point is more important than it might seem: transporting a fully assembled tower 100 feet tall is an awkward and expensive business.
In an empowered product team, the product manager is explicitly responsible for ensuring value and viability; the designer is responsible for ensuring usability; and the tech lead is responsible for ensuring feasibility. The team does this by truly collaborating in an intense, give and take, in order to discover a solution that work for all of us.
However, in a feature team, you still (hopefully) have a designer to ensure usability, and you have engineers to ensure feasibility, but, and this is critical to understand: the value and business viability are the responsibility of the stakeholder or executive that requested the feature on the roadmap.