Quality does matter
As an A&P mechanic for 20 years I can
answer your question and give examples
to my answer, most nuts and bolts on
aircraft are steel, but most aircraft
structure itself is aluminum. A poor
quality wrench will strip the head off
of a bolt much easier than a high
quality wrench from Snap On. Taking
into consideration that most bolts on
aircraft are located in areas with very
limited access, you now have a bolt
that no wrench will remove, even if
you have access to use power tools
trying to drill out a steel bolt in an
aluminum structure you run the high
risk of damaging the aluminum
structure getting the bolt out. So now
the Snap On wrench doesn't look that
expensive. I have personally seen
this happen several times in Aviation
costing the operator many thousands
of dollars and a couple of mechanics
their jobs.