Why did the cities seek to free themselves from the power of the lords?

Why did the cities seek to free themselves from the power of the lords? What are the reasons for the emergence of handicraft workshops in cities? What are the goals pursued by the shop charters?

The power of the lords also meant duties in their favor. The cities did not want to pay. Some cities had the strength to free themselves from the power of their masters, so they tried to do it.
It is easier for artisans to survive by cooperating with each other, rather than being hostile. So they found a form of such an organization of their work that corresponded to this, that is, they created workshops.
The main purpose of the guild charters was to provide benefits for all artisans in the city as a whole, even to the detriment of the interests of some of them. Therefore, it was forbidden to make things not only worse, but also better. So that everyone has an equal distribution of products.