A lot of times it comes down to conflict of interest. They are hired by the agent who is only interested in selling the home and getting the commission.
Even when they aren't, finding a reputable one who will actually do a good job is extremely difficult. Most are just looking to run through a house as fast as possible and collect their fee. There isn't some directory of problems they've missed. As far as I know there isn't any way to recover costs from them over issues that they missed and caused you to buy a home that you would not have given the problems. This makes them quite prone to being a rubber stamp and yet another fee for home buyers.
Even when they aren't, finding a reputable one who will actually do a good job is extremely difficult. Most are just looking to run through a house as fast as possible and collect their fee. There isn't some directory of problems they've missed. As far as I know there isn't any way to recover costs from them over issues that they missed and caused you to buy a home that you would not have given the problems. This makes them quite prone to being a rubber stamp and yet another fee for home buyers.