The history of counting AP Science as 1.5 credits stems from having to spend extra time at school to complete the labs, or actually having a lab period assigned. If a school district still wanted to award 1.5 credits, they would merely split the class into AP Science (1.0 credit) and Science lab (.5 credit). For example, AP Bio and Chem count as 2.0 credits in Lewisville, they are just smart about how it’s catogorized:
https://www.lisd.net/cms/lib/TX01918037/Centricity/Domain/2632/2017%202018%20CDG%20Final.pdf
Credits aren’t actually weighted, Texas is fairly strict about credits needed for auto admit, and also what counts as “class time” for attendance. Counting AP Physics C as a 2.0 credits is generally accepted because most schools split it into two courses: Mechanics and Electricity and Magnetism, but many also just count it as one credit.