This does seem to be holding back a lot of people from trying out DL in production. There are some advantages to using transfer learning in the cases you mentio

This does seem to be holding back a lot of people from trying out DL in production. There are some advantages to using transfer learning in the cases you mentioned (eg models not generalizing for watermarks or differences in training and testing). Although there are still quite a few cases where the best pretraining and large data don't work. Two major areas of advancements (current research) are automatic model architecture selection and automatic parameter tuning to help in making DL more accessible.