If I would need to hang cabinets, I would try to do my best and learn how to do that, so in case of falling, I can fix them on my own. Handyman does not need to care about quality of their work, it should be just enough. They know that you will come back, because you do not know how to hang those cabinets. It is in their interest to not do the work perfectly, because this means more work and more money.
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@rqm