Maybe trust was not the correct word; you always are in control of your coins but you are using a third party service: they could collect data, they could be forced to provide data by other parties, they could shut down the service overnight, etc…
Moreover, Wasabi works with chain analysis companies while it is not so clear how anonymizing is Whirlpool considering that the majority of the users are not using their private full node and so Samourai knows the zpub of almost every users that use their services…