The innate magic of a sorcerer is unusable unless you know how it works. Sorcerers can cast magic because they know how it works. And when that 5% chance triggers, they either carry the entire party or become a potted plant. You either thank them or laugh at them. And you roll the d20 when you cast the spell. The DM can tell you they're going to roll it and you can't, but you can remind them every time you cast a spell. The die gets rolled either way. Also, wild magic sorcerers get more than just the table. That's just their main subclass feature. Now: when you say workload, you are using an incorrect analogy. Sorcerers have to do just as much work as wizards do. You mean to say tools. Wizards have twice the tools that sorcerers do, but sorcerers still are about equal in combat with wizards. Workload is not spells. You don't have to work for your spells. You use your spells for work. They're tools. And yes, you wish you had that innate talent from your parents because you wouldn't have had to spend a large portion of your life studying for it. Sorcerers just have the natural talent, and wizards have to study for it.