Because there are four options to agree and only one to disagree. I would have thought a fair survey would be more along the lines of strongly agree, slightly agree, don't know/no opinion, slightly disagree, strongly agree.
Take the one about politicians for example. You might think that most politicians have genuinely caught covid but you only have to have doubts about one and that puts you on the agree side when actually your disagreement is just not as firm as it might be.