Those are after he meets the gang tho. We don’t see anything of Anakin before meeting the gang. With Luke, you know his story before meeting Obiwan.
In ANH we see the world up until that point through the eyes of R2 and 3PO. We learn who Luke is through them.
In TPM we see the world up until the Tattooine arc exclusively through the eyes of Qui-Gon and co.
The only difference is the amount of time it takes for us to meet Anakin - perhaps that’s what you’re pointing out. If Obi-Wan were the POV in the first act of ANH, then maybe it would be comparable. If Anakin were the most interesting character in the film with a more prominent role, then having him show up so late would be an issue.
All my opinion, obviously.
Obiwan and gang are used to introduce Anakin much the same way R2 and 3po are used to introduce Luke into the story, true. Difference is though in the pacing and timing. This works with Luke cause there is little action else wise, especially when you consider the original cut where Luke is seen with his friends, and spotting the space fight from his binoculars. This original cut didn’t work because aside from the opening battle, there is little other action till they get off the planet. So by cutting his early scenes, they push the pacing quicker.
TPM has much more action on the other hand, to the point that when Anakin comes in, it slows the story quite a bit (so does Corasunt). ANH we get one space fight, then droids are captured by Jawas, then they meet Luke. TPM on the other hand, you get a battle on the donut station, then they save Jar Jar, an Invasion of Theed, Attacked underwater by sea creatures, rescuing the Queen and men, then the pilots, then a space fight as they escape- Then they finally meet Anakin, to which there is a podrace, Quigon vs Maul, then Climax. Its all front loaded pacing wise, where as ANH built more like the first Matrix movie. Slowly building to the climax.