There is something wrong with your search. Your methodology is off somehow.
To illustrate one way to search for some of this information. First I looked for appropriate classifications in the newish CPC patent classification system. I used a rough google patents search and found one patent in the category and saw it was classed in CPC G05D1/0088.
The definition for that class is "characterized by the autonomous decision making process, e.g. artificial intelligence, predefined behaviours" it is hierarchically under G05D1 "Control of position, course or altitude of land, water, air, or space vehicles, e.g. automatic pilot ".
The CPC provides a list of other classes that are relevant for a complete search. The G05D area relates to control of many kinds. The B60W are relates to vehicles. I just used the primary class.
Using just G05D1/0088 I did two searches at the USPTO patent search site (not normally a recommended search site) one for 2017 and one for 2021. About four times as many hits for patents issued in the US in 2021. 1297 vs 325 hits.
I could have used Google Patents Advanced and found about the same answers. About 1,317 results in 2021 and about 302 results in 2017.