Traditionally we control access to our houses with "something you have": a key. This works pretty well, until you have a visitor arrive when you're not home to give them a key. The traditional way to handle this is to hide a key (under the mat, in a flower pot, etc), turning this into "something you know" (the information about where the key is hidden).
I've talked to a few people recently who've been enthusiastic about swapping traditional keyed house locks out for combination locks, and while I do see the appeal they're somewhat expensive and require batteries. But they're definitely a more secure way to implement access conditional on "something you know" than hiding a key.
Another option to consider, however, is a combination key lock box, sometimes called a "realtor box":
You set a combination on it, and then store a spare key inside. It is more hassle than a pure combination lock for access, but for a our house it works well. People generally carry their keys, but we still have a reasonably secure option if someone forgets theirs or a guest arrives while we're out.
Yes, but bumping requires a carefully modified key. These are tricky to get right, only fit one keyway each, and are often illegal to carry.
You could also use a picking gun for a low-skill attack, but they tend to be expensive and noisy.
On the other hand, decoding the kind of lock pictured in the post can sometimes be done without any tools at all, or may require a cut-off bit of metal from a soda can. And an alarming number of key safes (and, worse, gun safes) can be opened by inserting a bent wire between the lid and the case, and manipulating the locking mechanism directly. Once you know the easiest way in, no real skill is required.
Oh, and we can copy keys from a photo now, so an attacker doesn't even need to put hands inside the box to silently compromise security.
In general, we should prefer to never protect a security device with a weaker security device.