Most people are only audited once. Audits are happening all the time. Automatic audits from matching income are increasing in frequency because the IRS is matching more data every year.
I think that a lot of this is false correlation, meaning that an audit and political activity/association is only coincidental.
But, I think the question should be asked, especially in those cases where no deficiency was alleged. I went through one of those in 2012. Even the investigating agent admitted it was a waste of time, and after over $1000 in fees, my audit was closed with no change.
Somewhere, there is a record of why I was selected. If it was at an agent’s discretion, I want to know why. If they won’t say, then they deserve a visit from the FBI.