Why was Toyota Yaris and Honda Fit discontinued in the US?

Those models began to cost too much to make for their poor sales numbers.

EVERY one wants a TRUCK or an SUV now!  SMALL CARS are not selling well  SO they do NOT import them! They are NOT not safe anyway!  The YARIS was an ABORTION anyway! the ONLY TOYOTA not worth much but GREAT fuel mileage! FEELS CHEAP and UNSAFE, the YARIS! Bet a nice used BMW or AUDI or even a FORD FUSION or FOCUS! They are WORLD CLASSS cars! If a YARIS gets HIT by a truck or an SUV< you can consult a MORGUE! IF you like SMALLER cars get a SAFER VW GTI or a GREAT used AUDI TT coupe or convertible! AND SAVE your LIFE! USING CARS.COM see the GREAT used BENZ CLK 240 models from about 2000 or so! They now are CHEAP under $10K and VERY VERY STRONG and MUCH safer! >>AND you can STIL get financing as they are SAFE and RELIABLE as well! CHEAP insurance, tehy have ALL the safety features! 

They don't sell enough.  When gasoline was cheaper, people did not mind buying SUVs and benefit from their versatility.

Cause us americans like big gas guzzlers.

They were not selling well and the margins on these cars are small.  Not a good business strategy to continue making them.  You can still get a Hyundai Accent or a Mitsubishi  Mirage or a Toyota Prius C.