1. Software costs next to nothing to produce. Why is it so easy to have startups in this sector? What is the overhead of a software/web company? It is almost all intellectual. Ask Microsoft. Pure profit.
2. It is difficult for examiners to find prior art because there is no "official" channel for "publishing" software research that they recognise. There is much know-how that is common knowledge among developers but is never published in any paper, textbook, standard, RFC, etc. The "database" for searching all these sources may end being a web search engine. That is not ideal.
1. Drugs are very expensive to produce. Not only the research, the equipment, the staff, but compliance with the regulatory regime. There are no protections against bad software to protect users (developers operate in a wild west type atmosphere), but we have many rules about medicines. These are designed to protect patients. Can you imagine an unregulated pharma industry? Profits take precedence over safety. It would be very dangerous for patients.
2. There is a littany of journals that public chemical, biological and medical research and they can all be searched easily in combined databases, to which most all pharmaceutical patent owners subscribe. It is not too difficult for examiners to find prior art and establish publication dates.
These are my thoughts.