Hawkeye technology is practical in tennis because you have one ball and no bodies in the way. At the goaline in football would be impossible because there are at a minimum 12-14 bodies crashing together in a scrum as said ball carrier is hunkered over a ball we can’t see, trying to get over a line we can’t see clearly.
Having been there as a HL or LJ in high school football back in 80’s & 90’s, you have to position yourself, as they do now in college, HS & NFL, right on each sideline (so as to not be in the way of a play, sweep, block, etc. Those 2 officials are the only 2 who can signal if the ball crosses the plane. Thanks to good replay angles, especially overhead, you can see the ball where no official has a chance to see it until the pile unpiles and you see where the ball is laying like back in the old days. (Same as fumbles are done now😁)