When you look in the car, there are only a very limited number of things you expect to be there. If you're a mechanic, you've seen this model before, and it'll be pretty much identical, down to the last bolt. You need to assess the condition, and that'll affect the cost, but even so you can make a pretty good estimate from a glance.
Every piece of software is different. By the time you know what's going on in there, you're almost done. You have to look, but you're still going to be making a lot of assumptions. Assumptions that can throw you off by a factor of 10 -- or even make the fix literally impossible.
That doesn't mean we can do without estimation, even in software. You have to make plans and allocate resources. Just be prepared to change the plans -- and make plans that can accommodate the changes.
Every piece of software is different. By the time you know what's going on in there, you're almost done. You have to look, but you're still going to be making a lot of assumptions. Assumptions that can throw you off by a factor of 10 -- or even make the fix literally impossible.
That doesn't mean we can do without estimation, even in software. You have to make plans and allocate resources. Just be prepared to change the plans -- and make plans that can accommodate the changes.