»On the interpretation of (parking) signs

This morning the duallie white pickups were double-parked thick and deep on Scott St. A policeman stopped by and said that he had a mind to tag the cars, so I called the DPT. The contractors' pickups were double-parked because the curb spaces reserved for their use were taken, despite the No Parking easels and work permits which have been outside since August.

A dutiful DPT officer (the local chief, he proudly informed me) came out, tagged the two cars, and called for a tow. He checked the plates on the cars, and told me that the first one belonged to someone who lived nearby; would I mind if he tried ringing their bell? Of course not -- as long as the cars moved soon, I didn't care how he did it. (Aside: I remember being woken up early one morning when Arshad's car alarm almost had cutie towed from a spot next to Brother-in-Law's; I was impressed that the police were so diligent.)
A few minutes later an angry woman stormed up, steamed because she said that she's seen people parking there for the past several months. I could hear her arguing with the DPT officer outside; he told her on no uncertain terms that she needed to move the car before the tow-truck showed up. He reminded her that other people's behaviour is no excuse for her not heeding signs.
She walked into the basement, where I was reviewing some work with a HVAC contractor. Things got worse: she refused to leave the basement, and I tried moving towards the door but she wouldn't budge. She suggested that I have more respect for my neighours; I reminded her that a city-mandated mailing had gone to all property owners and tenants in May, when we applied for the DPT permits, and that the permits themselves, along with standard warning posters, had been posted since August. This didn't carry water with her. I kept moving towards the door, and she had to step backwards.
She railed against the ticket; I pointed out that the signs read "Tow Away No Stopping". She said that she couldn't read signs. The DPT guy calmly told her that if that was the case, she shouldn't be driving.
The car that she moved was filled with trash bags and miscellany: even the driver's seat had a rubbish bin on it. I didn't recognise it (this woman usually drives a blue minivan), but know the woman. I even believe that she can't read the No Parking signs, but also know that the signs are visually useful, even if they're not literally understood.
Everyone understands getting towed, though. I was looking forward to seeing at least one car up on a tow, but the other driver came along just as the first woman left. He was all in a hurry to have the contractors move their trucks, so that he could leave. The contractors gave him hell, saying "If you knew how to read a sign, this wouldn't be a problem."