It's true that a lot of people around SF are good with the honor system and dutifully tag their Clipper cards when boarding Muni buses and light-rail trains. But do the overwhelming majority? That is what Muni claims, via an estimate from a 2014 survey that they say in a blog post this week will be conducted again this year.

But how does this survey work, exactly? They ask people on a cross section of Muni lines if they actually paid and tell them it's for a survey and they're not busted?

According to their data, fare evasion was down from 9.5 percent in 2009 to 7.9 percent in 2014, with total estimated uncaptured revenue down from $19.2 million to $17.1 million. But in the several years since all-door boarding was adopted, allowing more people to slide onto buses via the backdoor without having to look a driver in the eye or flash a transfer, can we really expect that fare evasion has continued to go down?

Don't get me wrong, I'm all for all-door boarding. But admit it: You've run out of money on your Clipper card and boarded via the backdoor once or twice and assumed you probably wouldn't be caught, right?

Sure, there are occasionally fare evasion inspectors who will board buses and check everyone's proof of payment at certain Civic Center and downtown bus stops, but is Muni being a little optimistic when they say "contrary to concerns that all-door boarding would encourage fare evasion, it turns out that the possibility of receiving a citation at any time makes us all more likely to pay"?

Even they admitted in a report on the all-door boarding program that fare evasion inspectors are only kind of a deterrent. "Since some customers would probably continue to avoiding fare payment, it is unrealistic to expect that the SFMTA could recuperate all $17.1 million [in lost revenue] even with greatly expanded enforcement resources."

Discuss.

Previously: Here's Why You Should Fight Your Muni Fare Evasion Ticket