Because without that warranty, nobody would buy them.

Think about it. If you knew something was unreliable, would you buy it without a warranty? Their warranty is their saving grace, and TRUST ME, they do EVERYTHING they can to get out of it. If you havent had every service done at the dealer, you are in for a fight to have them honor it. And it is non-transferable, so the only way you get the warranty on used cars is if you pay too much and buy CPO.

well built cars don't need warranties.

It's just a way for Hyundai to try and claw back some trust that people lost in them

Hyundai and Kia offer the 10 year warranty as a marketing ploy to entice people to buy their garage cars. At the end of the day it is much better to have a good product than a good warranty. Plus the 10 year warranty is a power train warranty not a bumper to bumper warranty. Also, while the warranty is good for 10 years, it is only good for 160,000 kms (100,000 mi) which is really low. If you were to drive 20,000 kms (12,000 mi) /year then in 10 years you would have put 200,000 kms (125,000 mi) on it in 10 years.

Well their vehicles are OK up to 100,000 miles or so, so if they engineered it for that they feel confident enough to offer their 10 year/100,000 mile warranty.  They are also trying to grab market share and stand out from the competition, so makes sense for them to offer this.  Whether they honor every warranty claim is a different story, and their dealership experience (Hyundai/Kia) is terrible!

I remember when dodge trucks had bumper to bumper warranties. They needed them. Toyotas and Hondas don’t. At least most of them don’t. 

If you read the warranty closely, and have your attorney with you, you'll see that it's sort of like those Medicare Benefits ads all over tv saying you can get free this and free that.  It's a crock.  For example, the ac system is warranted for 10 years, unless you turn it on.

Think of it, most of the time lets say the engine blows up at 120k miles, but the warranty is only 100k miles so it won't cover it. If it blows up at 20k miles, they will have to fix it or find an excuse to not fix it whether the warranty is 30k or 100k. 

The warranties are NOT that great. If you buy the car used, you may be SOL

You have to look at the history of Hyundai in the United States. The original Hyundai Excel which as I recall went on sale here in 1986 was truly (to coin a phrase) a rolling pile of junk, based on obsolete Mitsubishi technology. The cars quickly gained a reputation barely above that of the Yugo.

Hyundai did improve their quality over time to the point where the cars would generally go 100,000 miles or so without major problems. They instituted the long warranty as a way to overcome their early bad reputation and entice people to buy. Having done that they are pretty much stuck with it at least in the U.S. since the long warranty has become an intrinsic part of the brand. Also many people believe the long warranty equates to higher quality than competitors.

I like your question. Warranties offered by manufacturers are all part of big business.  Yes the manufacturer will probably have to replace some transmissions, but they will make it up in volume from all those buying their cars because of that warranty 

Well it makes sense. Think of two scenarios, the warranty is 50k miles or the warranty is 100k miles

If the engine blows up at 120k miles like they are known to do, then its out of warranty either way.

If the engine blows up at 30k miles which is farely common for a Hyundai, they either have to cover it or find an excuse not to cover it either way

Plus that is the only advertising they go off of ("more safety tech than Toyota Honda or Nissan" "better warranty than Toyota Honda and Chevrolet")