S. Zayd Enam:

However, machine learning remains a relatively ‘hard’ problem. There is no doubt the science of advancing machine learning algorithms through research is difficult. It requires creativity, experimentation and tenacity. Machine learning remains a hard problem when implementing existing algorithms and models to work well for your new application. Engineers specializing in machine learning continue to command a salary premium in the job market over standard software engineers.
 This difficulty is often not due to math – because of the aforementioned frameworks machine learning implementations do not require intense mathematics. An aspect of this difficulty involves building an intuition for what tool should be leveraged to solve a problem. This requires being aware of available algorithms and models and the trade-offs and constraints of each one. By itself this skill is learned through exposure to these models (classes, textbooks and papers) but even more so by attempting to implement and test out these models yourself. However, this type of knowledge building exists in all areas of computer science and is not unique to machine learning. Regular software engineering requires awareness of the trade offs of competing frameworks, tools and techniques and judicious design decisions.