I have two tikuns at home, the Simanim and Mishor. In both of these, the column with Az Yashir (Shirat Hayam) is printed smaller than the standard size of the tikun. In the Mishor tikun, the columns with Ha'azinu are also printed small. In the sefer Torah at my shul at least Az Yashir is regularly sized, i haven't checked Ha'azinu. Why does the tikun print them smaller?
In a standard Torah scroll they are indeed the same height as the rest of the columns, but they are wider than the regular columns. To keep the proportions right and have it fit on one page, it looks like those printers scaled the whole column down to page width.
Rambam writes (Sefer Torah 9:10) that in his Torah scroll the columns were 4 finger-breadths wide, but the columns of the songs were 6 wide.