It was suggested to replace my brakes as soon as possible due to them being honest heavily rusted. You can see a picture below. I'm not sure whether what I was told is right because, as I see, rust is not on the rotor, only on the pad. While I know rust can spread quickly, I don't see any imminent danger.
I'm going to ask for a second opinion from a professional soon, but in the meantime I would like to ask the SE community: do my brakes need replacement?
Without having seen the backside of the rotor or the thickness of the brake pads themselves, from what I can see I'd say your brakes are far from needing changed, and especially not due to any little bit of surface rust which is present.
For the rust which is present, it is easily explained. When brakes are used they get very hot. Except for a few exterior coatings which prevent this, most coatings/paint heat up and peel off, leaving a nice fresh surface of bare metal behind (even more so if there's no coating in the first place). As you probably well know, bare iron or steel will rust very easily. The cast iron of this rotor is no exception.
The apparent smoothness of the side of your rotor we can see leads me to believe you have plenty of pad left at least on this side (the inside may be a different story). Usually when the brake pads get shallow, they start digging into the rotor and will cause all kinds of valleys and ridges. They may be large or small, but you'll definitely start seeing relief on the rotor surface (not always, but in a VAST majority of the cases). As smooth as this is, I'm not seeing replacement being an issue. As someone else stated somewhere, if you're at 5mm thickness of the pad, consider changing it soon. If you're less than that, you really need to get it changed for safety reasons.
From seeing what we can, I'd not have an issue using these brakes. They look in fine shape.
From that photo, I don't see any problem. That whole assembly looks in good condition.
On the left of the photo is the brake caliper. That holds, inside it, the two brake pads (made of a friction material, not iron). If that's 5mm (1/4") or more thick, you don't even need to change the pads.
Based on what we can see in the photo, NO. But we can't see the backside of the rotor, or the brake pads. And we don't know how well this was communicated from the technician to the service writer to you. You could be looking at the wrong wheel or they could have been thinking the brake fluid had a rusty discoloration. They might have suggested replacing the brake rotor because it was rusted seized to the hub.
What you can see there is a very typical condition of the rotor surface. Think about it logically, the friction between the brake pad and rotor is what makes the brake function. Do you see any rust where the parts contact?
This is an example of unacceptable rust:
Most rust on brake rotors is cosmetic and will be scraped off with normal use if the vehicle does not sit for long periods.
Rust is a fact of life for rotors because the best metal for them is highly susceptible to corrosion. It is an issue for car manufacturers - the cars sit on the lot for months waiting to be sold and the rotor rusts slightly everywhere but where the brake pad seals moisture out. The odd variation in thickness snowballs when the car is driven and 10-15 thousand miles later the customer comes back angrily with pulsating brakes. GM developed a new rotor material/technique to avoid the issue:
https://media.gm.com/media/us/en/gm/news.detail.html/content/Pages/news/us/en/2011/Nov/1130_fnc.html
When you do service the brakes use dealer parts, or the most expensive or second most expensive aftermarket brand. Change the brake fluid, and don't overlook that the tires are what actually stop the vehicle.
For me, the pad friction surface looks fine, the only question would be about the thickness of the disc and the thickness of the pad material. The disc itself has a wide working surface so get another opinion or two....
No you don't really need new brakes, but if you feel that your car needs a longer distance to a full stopp, then I would think about to change them. But as far as I see on the foto; I dont see a problem. My dads car also had rust on its brakes, after a couple of hours driving the rust was scraped off. Today he is driving with the same brakes. I give you a tip: test your brakes at the countryside at a long opend road. Test it under any condition: fast-slowly driving, pull the handbrake, maybe under wet conditions!
Rust/corrosion is responsible for brake pad failure that can be directly responsible for noise AND significant safety issues. You may be interested to review what was recently published in Auto Dealer Magazine on the subject of rust in braking: https://www.autodealertodaymagazine.com/355258/opinion-aftermarket-brakes-are-a-rusty-menace
