Because they can!
Summer vacation, Day 1: Spend an hour getting a 4-year-old and an infant ready to leave the house. Drive to the pool. Marinate in pee water for 30 minutes while you rock a cranky infant.
Tell 4-year-old to stop drinking pee water as you ponder the odds of all of you getting that parasitic diarrhea-causing infection you read about a few weeks ago. After the third time, pack up and leave because you're not feeling lucky.
Four-year-old has a psychotic break because she doesn't want to leave. Wonder whether 11:30 am is too early to start drinking.
Summer vacation, Day 2: Spend an hour getting a 4-year-old and an infant ready to leave the house. Drive to the temporary amusement park near your house. Realize it doesn't open for four hours. Your pre-schooler devolves into tears because she was promised rides. Cite some Buddhist bullshit about the nature of suffering and expectation. (The wise Siddhārtha Gautama once said, "Suck it up, buttercup.")
Go back when it opens and realize your kid is tall enough to ride three rides. Wonder why the boat that goes in a slow circle has a height requirement.
Pack up after three rides while she bursts into tears because she wants to ride all the rides. Agree that, yes, you too wish this sucked less.
Guide her through the park, past the "hand-dipped corn dog" stand, secretly grateful that you do not have enough cash to make that a reality. Listen to crying because you're not buying junk food. Wonder why everything wants to give you an Oregon Trail death.
Summer vacation, Day 3: Plan to let both kids watch TV all day. Everyone will be happier that way,