What do you mean by rigorous? I hear that word all the time but everyone has a different meaning for it.
This statement is misleading to an extend. ET are able to engage in design but it might not be complex design. Take the role “Civil Designer” for example both ET and Engineering majors can do the job. It requires using computer aided design software like AutoCAD to draft, scale, and fine tune existing drawings and plans for roads, for bridges and other construction projects. Since both usually have taken computer aided design courses. So I have see no reason why an ET candidate would not be consider for that position. Unless of course if the employer refuses to consider the ET candidate regardless if they have the credentials or not.
Second, only in the United States and Canada that ET candidates support engineers. This is not adopted as one standard throughout the world.
Yes, because the engineering board choose to make it that way. It doesn’t mean that there is NO “flaw or imperfection” to that standard or system. There are actually engineering bodies that push for PE licensures beyond an undergraduate engineering degree such as the “Raise the Bar” initiative connected with the ASCE.