Interesting,
Most manufactures save costs by offering a rope start.
They do not equip them with all that it needs for electric start other than providing a batt-tree.
Some manufactures will provide a ring gear on the flywheel if is is part of the flywheel as cast, and some also have bosses for the mounting of a starter motor.
some even have holes in the bosses but not tapped for bolts.
also some engines were never designed for a electric start so no provisions are provided in anyway for a starter/system.
most do not have a charging system if it is a rope start.
There are some 110V electric start that provide no charging system like toro and others, usually on a snow blower/thrower situation.
Most times unless a donor engine is available inexpensively, it is not cost effective to convert to a self starter application.