car seats pissing me off

Ashley • One baby girl, born March 2016. Married. Live in WVa
Our girl is 9 almost 10 months old. We love her infant seat. Easy to use, install, wasn't a billion dollars. 
Now we're looking for her convertible seat. And it is a giant pain in the ASS
1) why are car seats so damn expensive? 
2) why can't I test it out before I buy it
3) why can't they make the bigger seats with changeable bases? So I don't have to buy two I can buy one and two bases like the infant seat? 
4) why are some $45 and other literally $400? 
5) how am I supposed to know if it'll go into my car if I can't test it out first ?
6) what are the minimum standards a car seat has to meet to be sold in America? 
7) why is this one of the many MANY things people don't warn you about/help you with before you have kids?!?!! 
8) and why WHY do websites and other moms always make you feel like you will be murdering your child if you don't buy the $400 (FOUR HUNDRED DOLLAR) car seat????? 
I want my kid safe. I want her seat to stay in tact if there is a crash.  I want her to be comfortable. But I cannot spend 400 (or hell 200 on one car seat!) we have to have two seats. Dad drops her off at the sitters and I pick her up we can't switch the seat every 8 hours.