Developers generally do what they're asked to do.
Given the usual project variables of time, cost, resource and quality, take a guess at what is usually bottom of the average corporate priority list? (Actual priority not stated priority btw)
At the moment, hardware is generally good enough to accommodate mediocre quality software for most applications. If that changes then commercial pressures will shift towards better quality code.
Currently, there's very little recognition or reward for elegant and efficient code in most places.
Also, leave off the software engineers. It's a discipline that's what, fifty years old? It's also in some cases the most complex engineering task there is.