As a flight instructor we teach risk mitigation which is the third step in the risk management process. Everything in life has risk. You must asses all aspects to make risk low. There seems to be throughout TBN lots of armchair safety pilots.
Then there are those that do. It doest not mean they are unsafe because they had a need and filled it. Risk mitigation looks at all aspects. Is it safer to do what you need with a ladder vs a manlift? Or maybe scaffolding? Or climb a tree? Aircraft have hydraulic hoses going to the oil coolers and if they break the flight is over and the plane is coming down. What if your on departure and can't turn back. It's risk mitigation. It is low.
On a manlift the risk of hydraulic failure of any kind is extremely low on well maintained equipment. You have higher risk in falling out of a manlift just as a tree stand if you don't use a safety harness.
And probably the highest risk in using a manlift isn't the tractor at all but rather the other person at the controls who goes oops, sorry bout that...kerplunk