There are a lot of different reasons. The cynical take is that the time to ROI is too long. If it is going to take 10 years to turn a profit the executives do

There are a lot of different reasons. The cynical take is that the time to ROI is too long. If it is going to take 10 years to turn a profit the executives do not want to pull the trigger on that because they will be out the door in 5 and never get the payments. Another possibility is that all the low hanging fruit is gone. So the marginal improvements do not return large financial gains.