Ridership on SF's historic cable cars, which are considered a must for many tourists, seems to be on the decline, and the Chronicle's Matier & Ross surmise this may be because fares went up to $7 a person, or because lines can be egregiously long during the height of tourist season.

The cable cars saw 20,600 rides per day as recently as 2014, but in 2016 that number was down significantly, to 15,500 rides per day. So far in 2017, the numbers are slightly better, at 17,511 rides per day, but the question remains why the popular attraction seems to be attracting fewer people.

M&R point to the slowness of the process at the Powell Street turnaround, where they observed a line of people a couple hundred strong on sunny afternoon in July, with "seven empty cable cars standing still," and there was no apparent explanation for the holdup.

But maybe there's something else at work here. The SFMTA is seeing an estimated $13 million in lost ticket sales on the cable cars, but in August we learned of a auditors' report that alleged that cable car operators were failing to collect fares from riders 37 percent of the time, and that operators were failing to ask for proof of payment from riders 70 percent of the time. Couldn't this be to blame for the apparent drop in ridership — i.e. there still the same number of riders, but fewer of them are paying or being asked for payment?

Related: Scathing Report Reveals Cable Car Conductors Fail To Collect 37% Of Cash Fares, More Stings Planned