I do not actually know why a fabrication company will go to the extent of making parts that do not fit well for the purposes intended. Maybe they lack attention to details or think the users will always find a way around it to make it useful just as you said...
The bolt hole could be widened out so it was not that large of an issue...
At times, it is necessary to personally see to it that you get good value for your money by doing some things yourself like you did designing the parts needed yourself. Most times, I prefer to do electrical repairs myself. That's my area of expertise anyway, but I also do painting myself. With that, I can experiment with different mixtures or designs and techniques.
I agree, thats why i was so blown away by this instance. Im sure the person who worked the day this bracket was made was probably fired.