I thought I was clear where I was looking - here, you may check for yourself: https://en.wikipedia.org/wiki/HESA_Shahed_136.
You presented the absolute maximum estimate as if it were the conventionally accepted value. That's incredibly misleading.
China operates fishing fleets all around the globe but Iran is not known for this so Iranian fishing vessel in western Atlantics will rise suspicions. An ordinary cargo vessel heading to the Central America on other hand may sail unnoticed.
It's a couple of hundred miles from the frontlines in Kharkiv, and the Russian border to the North is even closer.
The fuel tank is heavily segmented, so they are difficult to shoot down. When shot, they lose fuel but continue to the target. They get to the target with less fuel, but still get there. The HE them detonates the remaining fuel load.
A Shahid could do a 2500km mission, and arrive with a very small fuel load. That will be effective against targets that already have enough fuel to burn there, such as apartment buildings, petroleum energy infrastructure, office buildings, etc. Less so against places with little flammable material concentration such as hospitals, military installations (other than fuel and munitions depots), roads and runways, etc.
I think the furthest hits Ukraine has been able to achieve with drones were on a refinery about 1300km from Ukraine controlled land.
[1] https://news.sky.com/story/four-arrested-on-suspicion-of-syp...
[2] https://www.jpost.com/diaspora/antisemitism/article-890851