The scanners are near perfect on accuracy reading the barcodes. Unfortunately the codes aren't always correct. I had a piece of mail show up one day that belonged somewhere else. The human readable address was perfect. I put it back out the next day. A couple days later I got it again. Before putting it out again, I obliterated part of the bar code they put at the bottom edge of all first class mail. I never saw it again. By the way, that bar code is your 9-digit ZIP code, which you share with a very small number of your neighbors. Once the machines sort the mail using the bar code, your carrier only has to look at your street number to get it to you. In the piece I described, I shared a street number with the intended recipient, but it was a different street. Incidentally, the bar code is single error correcting and two error detecting. This means if you obliterate one bar of the pattern, it will figure out what it originally said and correct it back to the original. If you mess up two bars, it will know something is wrong and kick it out as an error. With more than 2 bars messed up, anything can happen.
Fifty years ago the USPS was organized as an "independant" agency and tasked with breaking even. The other powers that be then figuratively tied one hand behind their back and made it essentially impossible. Their service standards are set by congress and their rates are set by the Postal Regulatory Commission. If they want to change a rate, they have to argue their case in front of the commission (of which USPS has no voice in membership). Meanwhile congressional acts require things like delivery to every address 6 days a week (with rare exceptions). Try calling up UPS or FedEx and arrange for them to stop by your place every day to see if you have anything to send. Let us know how that works out.
