"But as soon as I walked in the manager criticized me for wearing a plain white t-shirt, and sneakers;"
I doubt he did -- if he is that unaware of legalities and proper decorum ... you should be glad you did not get the job
as for qualification ,,,, heck I could train a "good" worker in no time for said work
I cannot train (abide) a slacker who will not even were a dress shirt slacks and dress shoes to a job interview.... I agree why are you not working for your dad?
the simple fact is a good attitude and showing up on time and dress appropriate is the most import part of the job when a new hire is made., I do not let my repairment dress in sneakers and T-shirts -- no jeans either
at least wore worker khakis
what you do not understand a employer see you at what he figures in your best
EFFORT on the interview,, knowing after you have the job you will stop putting any effort in
you need to also have understanding of proper decorum
the problem is many many people are choosing to close business because the only hires they get now days are bad employees..... soon your only choice will be those mega business young people hate. While your under the impression business exist to provide jobs,,, the fact is they exist to make a profit for the owners and if not profitable they will fail to exist. All the T-shirt wearing holes in jeans and too short of dress people I hired NEVER were good workers.
While you have a great explanation for where what you feel is appropriate for the job you will also have excuses for being late, screwing off on the work day losing tools and stealing and doing the assemblies incorrect but good enough for your expectations