What date are we talking about?
Most websites show the year the company or website was founded and the current year, or the year the website was last modified.
It appears at the bottom of the page next to copyright (© copyright).
Does having the year out of date generate any problem or inconvenience?
Seeing the date not updated gives the impression that the content of the website is not up to date, or that the company no longer exists or that the website is not active.
This can generate mistrust when making an online purchase, contracting services or filling out a form, and therefore, causes a bad image.
Having the website out of date for a long time also lowers the web positioning of the pages in the search results, because Google and the other search engines prefer pages with more recent, or at least current, content.
How is the date of the footer programmed?
To always show the current year is a basic functionality of a website and programming this function is one of the easiest tasks in the development of a website.
By default, the vast majority of software used to make websites always shows the current year (Wordpress, Drupal, etc.).
If the date on the website is out of date, it's because the person who programmed it wanted it that way.
So why do so many websites have the year out of date then?
Many companies that make websites change the code that makes it always display the current year to one where the year doesn't change.
This way, after a year, they can charge clients for that work.