Forms that require two family names to be mandatorily imputed in separate boxes. Although this isn't a problem for me as my full name has indeed two family names, it can be for anyone not from any Spanish or Portuguese-speaking countries. In that case, one of the family names (the first for Portuguese-based forms, the second for Spanish ones) should be the maiden's name of one's mother.
A similar frustration is programs that cannot accommodate two-word or hyphenated surnames.
For example, a program we use at work to run background checks cannot accommodate any spaces or hyphens in the surname field. Not only is this bad for Hispanic immigrants who use both a maternal and a paternal surname, but also for a surname as simple as St James, and for the common Marshallese surname Chong Gum. So then we have to choose what to do: smoosh the words together with no space/hyphen, drop the second one, drop the first one...? At any rate, then, it's bound to not exactly match the way the surname is spelled out in every other program—many of which don't have that issue. Then, when one program needs to correspond to another program (such as background check and driving record), things get complicated.
Why did people set them up like this? Did it never occur to them that some people have spaces and hyphens in their names?