Almost any crafting profession involves practice outside of work; for example: painting, photography, sculpting, etc.

I also suspect many academic professions fall into this trap as well: mathematician, physicist, etc.

As a developer myself, I don't think this particular aspect is unique, instead I think it's a matter of perspective and what we value in life.

For example, many individuals if they see someone reading a phone as they're walking may look unfavourably upon them thinking something like "people glued to their phones, bleargh". However, if the same individual was walking reading a paper book instead, many would simply shrug it off as "that person is a studious individual / bookworm".