It's based on some US-Russia agreement signed in 2012 [0]
But I hear what you're saying.
I met a German family who had a custom-made camper van in Georgia. They told me they drove in Russia but their visa wasn't long enough. I told them I had a 3-year visa and they wouldn't believe me until I showed them my passport with my visa on it.
Do you know why this is ?
As an Australian citizen, I am a bit frustrated to have to limit my visit (planned for later in the year) to 1 month.