The use and value of salt

[Epictetus]

Supposedly, in early Rome salt was rare and valuable. Even Pliny thought that the word for ‘salary’ came from the word for ‘salt’ because soldiers had once been paid in it. But as time went on, did salt become more common and lose its value? Galen mentions peasants using it:

But I myself, when travelling as a young man into the countryside some distance from Pergamum... came upon some peasants… One of them straightaway threw some wheat into a pot and boiled it, and after adding a little salt, gave it to us to eat.

I would guess that if salt was rare and valuable peasants wouldn’t have any. How widespread and common was the use of salt?