I am not sure, software is a bit like a trade, you actually build something only it is virtual and if you build it they will come, nobody can stop you from building things.

Medicine, Law or consulting are services, not actualy creating any actual new value. They build their moat by making the license very hard to obtain and making one's status and prestige the most important thing. You do need licenses to do certain trades but they are usually not that hard to obtain and the prestige of the institute giving them is less important.