Why would anybody plant a box elder, much less beside a house?
The quick answer is that most plant themselves.
Getting into more detail, Box Elder (Acer negundo) trees are pretty darn useful. Make syrup from the sap or drink it straight. Eat the new leaves, inner bark and seeds. There is a type of edible oyster mushroom (Hypsizygus ulmarius - also known as Pleurotus ulmarius) that likes to grow on them. Make cordage (twine, rope, etc) from the inner bark. Weave the inner bark to make bags or wood splints for baskets. Make excellent char (think charcloth for Flint and Steel (aka F&S) fire ignition) from the inner bark or punkwood. The punkwood of Box Elder trees is one of only three punkwoods that in its
uncharred state has caught a spark from F&S for me so far. It is possible to make all parts of a friction fire bow drill set from a single Box Elder tree. Fairly light yet strong wood that carves and burns well. Of course objects made from the wood of Box Elder trees need to be cared for. On the tree the wood rots more quickly than most. Many native tribes used the wood for musical instruments. The native range of Box Elders was about half of the United States. People have planted them everywhere so they can now be found from Canada to Mexico, roughly triple their former range. The gorgeous greening up of last years branches is another sure indicator that Spring is right around the corner and one that I personally look forward to each year. Heck, they're also easy and fun to climb. None of which is surprising knowing it is in the Maple family. All in all, Box Elders are awesome trees.
I dunno, why would anyone want a Box Elder tree??