Why are certified copies of documents only valid for a limited period?

Because my physical personal documents are private, and I want to protect them. Especially my ID documents. Having to produce them frequently and unnecessarily is a form of surveillance I would like to avoid. Many countries that have national IDs, which is most, require their citizens to carry them at all times, even if they have other forms of ID they can produce. For example, if you drive every day to work, it’s normal to carry your driver’s license on you at all times. However, in some countries, the police can stop you and ask for your national ID in addition to your driver’s license. The latter is not enough. Hence, some people, to protect their national IDs, would rather carry a certified copy of it, because it is considered the most important ID document in their country. It supersedes passports and drivers licenses. They don’t want to risk losing it, because administratively, getting it replaced is a pain in the ass, and can take months. Marginalized communities also have an incentive to protect their documents, because not being able to produce them can marginalize them further. Consider all the American citizens and US residents who were arrested and locked up by ICE because they couldn’t “prove” their legal status on the spot. This is why I would rather carry a certified copy rather than my actual passport. But if certified copies are only valid for a short period, I constantly have to risk losing my passport. Replacing a certified copy is easier than replacing a passport, especially when you’ve made multiple certified copies in advance.