And if you're unable or unwilling to pay, they might go abroad elsewhere and offer their ideas or services to someone else.
You need to go through an expensive process of inviting foreign engineers, technicians, and craftsmen into your country who have the know-how to create such things. Likewise if you're an African or Asian country that just started the process of westernization, you can't just build a giant ammunition or cannon foundry because you researched a tech (like in Victoria 2). military (President Lincoln was offered to test it himself and ordered it to be produced) and Chile who evaluated it and adopted it to varying extents. Across the pond, the Spencer repeating rifle for example was developed by a private company and offered to the U.S. He then went around to various German states offering to sell the rifle and look for contracts to setup manufacturing facilities. Johann Nicolaus von Dreyse was the son of a locksmith who founded a private manufacturing company which developed it.
Using the picture of military technologies above as an example: a centralized bureaucracy didn't invent the famous breech-loading needle gun. But for a game that models history, does a traditional tech tree even make sense for the time period?