Things I don't understand

The two on the left are approximately the size of a nickel with a normal spread of their legs.  The one on top right is about the size of a quarter.  The one on the bottom left is about three inches/eight cm across.

1. Why Belgium is currently hosting so many public spiders.  I cross the ones shown here (plus a few more of the orange and black ones) every day on my way to the bus stop; they live in an archway connecting my apartment complex's central grounds to the street.  I passed a bridge this morning with a web, half of them occupied, strung in each gap between railing pillars.  I do not want to think about what this implies for the current state of the fly population, or what it could be like.

2. Why Ikea requires those buying a couch, a piece of furniture that is not flat-packed, to load the item on a trolley and drag it the full length of the warehouse to and through the check-out lines.  We then had to pull the thing to customer service and wait in line until one of the employees brought out the cushion covers for us.

The couch moved by customers and the cushion covers handled only by employees.

3. Why everyone in my building seems to have cheese with their lunch.  I understand that I am in Europe and cheese is a big deal around and inside the French border, but so are sausages and I don't see the refrigerator packed with them.  Even if gouda isn't the strongest cheese around, when the refrigerator houses more than a dozen specimens non-stop it can start to get a bit . . . whiffy.

4. Why if I print the values of variable x and get the list {172.15,172.25,172.35,172.45,172.55,172.65,172.75,172.85}, the test x == 172.15 never, ever returns true.  The test x == 172.25 returns true, but never x == 172.15.  The list is populated with ever possible value of x, and yet the test fails.  I lost the better part of a day and some of my trust in the logic of computers to that one.

That is a lot of incomprehension accumulated by a Tuesday.