Is it required for companies of a certain size to have an HR person?
Many companies assign human resource responsibilities to controllers or CFOs. Some of these professionals take the responsibilities very seriously and do their utmost to become experts to the degree that they can while juggling all of their financial/accounting work.
Others do not bother and that is unfortunate, as much damage can be done. Many businesses choose to think that what they don't know can't hurt them regarding employment laws and/or treatment of employees to maximize productivity and, thus, their return on the investment that they make in their workers.