Sorry about poor english. I think this may be a usefull feature. When Waze calculates alternate routes, calculate booth types: shortest and fastest. The on the alternate routes page shows them and allows me to choose witch is important to me.
Because Waze already has alternate routes feature, are you asking that Waze, when it shows the alternate routes, to identify the shortest and fastest?
I think choosing between fastest ans shortest is only relevant if you travel less than a few kilometers.
If I drive, let’s say 50 kilometers I don’t really want it to calculate how I could travel the shortest distance;)
Just this afternoon, I was on a 60-mile drive that involved several major roadways. The “show alternate routes” function gave me three choices: two had identical travel times but one was a few miles longer, and the third was a few minutes longer and a few miles longer.
Of the two with the shorter travel time, I chose the one that was also the shorter distance–my reasoning being that a lower average speed would probably require a little less fuel.
Indeed. You say that right.
You choose the shorter route. Not the shortest 
and that’s what kaszast was proposing.
? The shorter of the two fastest routes, was also the shortest of the three alternates that were provided. (The third was both slower and longer than the other two.)
Yes, but there is a difference between the shortest fasted route (wich is allready a calculated alternative) and the shortest possible route.
The shortest possible would just go straight through a village instead of around it for example.