One thing that's important to understand about Tasks in ServiceNow, is that all task records (whether they're changes, problems, incidents, requests, request items, catalog tasks, or tasks in any other table that extends the base system task table) are technically all stored in a single database table. Although in ServiceNow, you see them as separate tables, that isn't actually the case. This is due to the flattening of the task table.
Each task-extending table has a field called Task type [sys_class_name], which defines what type of task it is (problem, change, incident, etc.). ServiceNow groups records with the same Task type, and treats them as though they're all in separate tables, but in the physical database on ServiceNow's servers, they're technically all in one big table.
This fact has far-reaching impacts on the way that the task table should be handled, some less obvious than others. For example, say you want to create a new field on the Incident form: Assigned...