This is a very open question as you're putting various APIs / serialisation techniques into the same category. I'll only respond to the JDBC part, in case of which obviously none of the drivers use Java serialisation because the relevant database communication protocols are defined by the databases independently of any client technology (Java, PHP, .NET, Python, etc...).
It would be safe to assume that most similar API implementations work in a similar fashion behind the scenes, because Java serialisation is inherently Java-specific, and it is usually not a good idea to make any protocol (regardless of the purpose) language-specific.