An employer here can send a doctor to your home to check if you’re really sick if they’re suspecting you to abuse the system. If you’re not at home then you’re in trouble. It can backfire of course. My dad got a visit from a doctor hired by his boss when he was really sick, the guy did his diagnostic, and gave my dad a few extra days of sick leave because the doc found sending him back to work on schedule was not a good idea.