Why are full-width numbers and half-width pseudonyms still widely used in Japan?

Quite simply, this is because the popular habits caused by historical reasons cannot be eliminated immediately. Half-width katakana was made after the introduction of ASCII code table in Japan that year. They stuffed half-width katakana into one-byte JIS X 020 1. When the technology is limited, it does play a role and saves storage space. But in today's Unicode era, it has no effect at all, but has become the root of garbled code. The half-width katakana on the envelope label you mentioned is often made by the labeling machine. The old system cannot use Unicode. I'll force you to use it. I can't help it. Before smart phones, Japanese mobile phone systems were developed locally from internal code to UI design. In order to save display space and convey more information on the small screen (Katakana is phonography, so words are often very long), we deliberately use half-width Katakana. Other industries, such as news agencies and newspapers all over Japan, have been using full-width figures in order to calculate the number of words, and this habit has been preserved to this day. So now, even if you take the latest Shinkansen train, the news subtitles you see on the scrolling news screen are still full-width English and numbers. If you encounter longer English words, it is simply unbearable. But in order to keep the timeliness of news, this system is linked with the news agency system, so this is the case. Moreover, full-angle English numerals are also convenient for horizontal and vertical changes. At present, in Japan's printing and writing environment, almost half of the publications are still vertical. Different from Chinese, in many cases, alphanumeric characters of straight text need "vertical, middle and horizontal" functions to stand upright, and full-angle alphanumeric characters look more comfortable. (Of course, there are times when it is too late. ) In Japanese input methods, especially local input methods such as ATOK, by default, the full-width number option will take precedence over the half-width number, so most people are too lazy to switch when typing. In the network input environment, general tables need to be directly converted to other platforms, and programmers are lazy (with the current technology, it is completely possible to program and convert half-width and full-width characters without forcing users), so it will be very troublesome to use half-width or full-width fields. The power of habit is powerful and terrible, although it is so ugly.