If it’s the USA, then “iced tea” may actually mean “sweet tea” (an American South tradition), which is often prepared something like this:

• bring 1/2 gallon (1.9L) water to a boil
• place 8 large black tea bags in a 1 gallon (3.8L) pitcher
• pour boiling water over the tea bags in the pitcher
• steep 10-15 minutes, then remove tea bags from the pitcher
• add 1 dry cup (220g) granulated sugar
• stir the slurry until sugar is dissolved
• fill the pitcher to the top with ice cubes
• wait 20 minutes for ice to chill and dilute the tea, gently stir again
• serve

It may be a stronger tea, but so much sugar gets added (probably 3x what would be used to sweeten tea served hot) that you typically don’t notice any bitterness.

It’s primarily much sweeter due to the shitton of sugar