Being dead makes it very difficult to do the things needed for life. Americans have been told that they actually died trying to get a new SIM, retirees have been waiting for checks that have never come they need to pay for vital medicines and when trying to open a bank account.
Most mistakes are simple typos made when the clerk, maybe at the funeral home, a one-digit subs in the social security number for another. Errors also make people open to identifying theft because their SSN is published in Master Death File, but it takes several weeks for the administration to completely stop the number.
In the end it depends on the numbers. Because around 2.8 million people die each year, the error rate is less than 1 percent if around 12,000 are mistakenly marked as dead. However, mistakes are still frustrating for those who experience them.