That sort of thing seems to improve over time. The USPS has had automatic sorting machines for a long time. At first they could only read pre-barcoded mail. Humans had to key in zip codes. Then character recognition got good enough that printed and typed addresses could be read automatically. Some items were still rejected, and they went through manual stations that added a bar-code sticker.

Then manual reading was made remote. There were about 20 USPS remote envelope reading centers at peak. As the vision systems got good enough to read handwriting, then bad handwriting, those were cut back. Now there's only one remote envelope reading center in the US, and what gets there is really bad.

Tom Scott did a great video showing the last one in operation. They use totally unique keyboards with what is essentially a stenography system:

https://www.youtube.com/watch?v=XxCha4Kez9c