Technicians? But Doctors, engineers and architects are technicians too!
I think you mean the electricians, plumbers, roof repairers etc?
'Respect' is a subjective word. But considering that its proportional to the wage or salary received:
Their value of 'output' is less than that of the engineers etc. An engineer plans the whole building, as a result, he is in charge of the whole building. Whereas, the electrician is only responsible for wiring the electrical points. This results in the former earning more, and thus higher respect.
Personally, I think prioritizing occupations according to 'respect' is wrong. The money is a better measure.
Advantage of being a technician is that you can be creative, and work on your own pace!