The different lines are at the same AC voltage, but have different phases (almost always three phases), so there's an instantaneous potential difference between them. The lines need to keep the conductors seperated to prevent potential arcing chances to essentially zero even in wet weather. The higher the voltage, the more seperation is needed.
One could argue that the most important criteria to optimize for is insuring that the mean expected value is exactly 0.5. That is a more practical criteria than trying to allow super low values like 2^-70 which are indeed expressible as floating point, but just less important than maintaining the simple behavior of a proper average value.
It's common to find this kind of asshole behavior in residential real estate agents. It can be understood when you realize they get a commision as a fraction of the sale price. This does NOT make their interests align with yours! Unintuitively, it is usually in their interest to sell your home as cheaply as possible (!) in order to sell QUICKLY. They would much rather sell your $1M house in two weeks as opposed to a $1.2M price which would take them four weeks of work. Their payday in terms of income per week of effort is far far higher in the lowball case.. the one that screws you, their "client", out of significant money.
Technology is a dramatic counterexample. 1999's ASCI Red 1-2 teraflop supercomputer cost $46,000,000 1999 dollars. A 2 teraflop 2022 iPhone 14 costs $800. Even if you nitpick the computation comparison, there's still a 5 order of magnitude reduction in cost.