I'm working on finding out the impact of Covid.19 on commuting so income and distance will be relevant variables to include. However, these variables dont change from period to period, so it's unlikely to explain the change in commuting and not be statistically significant. Income is pretty stable and distance between cities is fixed across time and only vary between city combinations. But they're also important for the theoretical framework to include in the model.
I certainly know that the income level explains commuting but not the change in income. And i guess i would need many years to capture any significant change.