Wedding rehearsals are very useful when the wedding party consists of people of all sorts of different religious denominations, who might not know any of the protocols of a given church or temple.
At the rehearsal, the celebrant in a religious wedding walks everyone with a formal role (wedding party, flower children, ring bearer) through the entire ceremony. Details include the entry procession, precise seating positions, the bride and groom processing to the location in the church or temple where the vows will be exchanged, and practicing any bits like lighting candles, signing the register, etc. Anyone doing readings will be given instructions on using the microphone and a chance to practice the readings. There may also be some preliminary blessing and prayers that can be done at the rehearsal (which is usually held in the late afternoon/ early evening of the day before the wedding).
At a secular ceremony, the wedding planner will organise the wedding party at the venue, and bridesmaids/ groomsmen/ parents of the bride and groom/ flower girls and boys, and ring bearer will practice walking toward their seats, sprinkling petals, bringing the rings forward, etc. Again, this is usually a late afternoon/ early evening event.
After the rehearsal comes the meal, which was traditionally offered to out of town guests, with the wedding party and anyone else the couple wanted to invite. Tradition held that the groom's family hosted this meal and the bride's family paid for the wedding.
I'm firmly in camp 'If you can't afford to pay for your own wedding then you shouldn't be getting married', and so far, my two DCs have married people from families who felt the same. There was one secular ceremony and one church wedding. Both have had rehearsals and rehearsal gatherings, and both had wedding receptions - very different from each other but also hugely enjoyable.
Jaywalking - you can only legally cross the street at an intersection/ marked crossing point. Crossing anywhere else is jaywalking. I suspect the reason for this kind of by-law was pedestrian safety and reducing traffic disruption. Perhaps also the fact that there were trams and tramlines in many cities cities made it necessary to desigalnate crossing points. Many American cities have major streets that have more than one lane of traffic going in each direction, so taking a chance on crossing mid-block would be crazy.
As an Irish person with anarchical street crossing habits when I first landed in the US, I got yelled at a few times, but no tickets or cautions. Lots of horn blowing too. As a driver, it's easy to understand how chaotic it would be if people en masse decided to cross wherever they felt like it.
The fact that bus drivers will often wait for you if you wave wildly from the opposite side of the street helps prevent people thinking they need to take chances.