Your point fascinated me, and I reward you with best comment in this thread. I prompted GPT4 with this :

Tell me about viscosity in the terms of the four forces. I want you to use every force. Not just the ones that apply specifically to how viscosity works. Because all the forces are still exist, and in some ways still have an effect on how viscosity works. So tell me, in terms of the four forces, what is governing viscosity?

And she replied with:

Viscosity is primarily determined by the intermolecular interactions within a fluid. While not all of the four fundamental forces directly contribute to viscosity, they still play a role in determining the overall behavior and properties of matter. Here's an overview of how each of the four fundamental forces relates to viscosity:

Electromagnetic force: This is the most relevant force when it comes to viscosity. The electromagnetic force governs the interactions between charged particles, such as electrons and protons. In fluids, this force affects how molecules and atoms interact with one another. Attractive and repulsive forces between particles determine the ease with which the fluid layers can slide past each other. The stronger the intermolecular forces, the higher the viscosity of the fluid.

Gravitational force: Although gravity does not directly determine viscosity, it affects the behavior of fluids under certain conditions. For example, in a column of fluid, the pressure at the bottom is higher due to the gravitational force acting on the fluid. This pressure difference can influence the flow of fluids, particularly those with higher viscosity.

Strong nuclear force: The strong nuclear force holds the protons and neutrons together in atomic nuclei. While this force is essential for the stability of atoms, it does not have a direct impact on viscosity. However, the strong force indirectly influences viscosity by determining the types of atoms and isotopes that can exist, which in turn affect the overall properties and behavior of fluids.

Weak nuclear force: The weak nuclear force is responsible for processes such as beta decay and plays a role in nuclear reactions like fusion and fission. Like the strong nuclear force, it does not have a direct impact on viscosity. However, it indirectly contributes to the overall properties of matter by affecting the stability of atomic nuclei and the types of particles that can exist.

In summary, while the electromagnetic force has the most direct impact on viscosity, the other three fundamental forces contribute to the overall behavior and properties of matter. Understanding how these forces interact is essential for a comprehensive understanding of the physical properties of fluids, including viscosity.