Here (AU), since last year, businesses with fewer than 100 employees (99% of public sector firms) are exempt from unfair dismissal laws, and those with over 100 employees are able to dismiss anyone any time if they claim that part of the reason for the dismissal was for the "operational requirements" of the business. Being sacked on the basis of race, sex, age, pregnancy or family responsibility is still technically illegal, but pretty easy to get around.
Another trick is to make all your employees "contractors", or keep them as a succession of short-term casuals. Then they don't count towards your total, and they aren't covered by the unfair dismissal laws anyway.