The concern that most people are expressing is that you potentially don't know that a spider is there in order to avoid provoking it, whereas if you see a bear, you can usually just choose not to provoke it.

Having to be on the lookout for spiders, all those little things like checking your shoes before putting them on, are easy enough to do if you're used to them, but if you didn't grow up doing them then it can be a big adjustment, which is why most serious spider/snake/octopus/ect. encounters in Australia are specifically with non-residents or new residents. Meanwhile, not pissing off a bear that you would probably have to go out of your way to get close to anyway doesn't actually require any kind of lifestyle change.

When you're comparing people who grew up or have lived long-term with one of the other then they're going to view the one they're used to as easier because they know what they're doing and have already built up any necessary habits. However, most people who are commenting here have not grown up or lived long-term with either, and are looking at this with a mindset of someone being suddenly introduced to cohabiting with these animals with minimal preparation (like those tourists in Australia who account for the vast majority of serious spider bites).