They all have their own differing opinions.
Why do experts disagree on things?
An expert is a person having a high level of knowledge or skill in a particular subject.
But experts, just like you and I, draw their own conclusions.
Could be that we don't know everything! You might be the top expert in a field, but there are some things you don't know and you might be wrong. This applies to the scientists too. On the things they do not know, they go with what they think is the right answer.
Usually, when experts disagree, it is in a field that really has no solid consensus ... Such as politics or economics. Just because those fields involve the actions of humans, and humans seldom act rationally - thus are difficult to predict future events, even based on past events.
Other than differing opinions, statistics can be skewed. For example, they say 50% of all marriages end in divorce. That is a false statistic that has been around for a long time. The true statistic is half as many couples file for divorce each year, as those that apply for a marriage license. What so many people don't count is all the marriages that are neither filing for a license or a marriage.
You get two mechanics and tell them the the problem with your car and you will get two different diagnosis until they touch and see the car
Not really and not all the time.
In my field there is a bit of a disagreement over group selection vs individual selection. Still, there is no disagreement that evolution is a fact and that the theory of evolution explains much about the fact of evolution.
So, some pieces of things may be disagreed on but the overwhelming consensus is agreement on the whole. Take climate change for instance, the faction that disagrees with the consensus here is minuscule.
Of course none of this applies to such rigor-less disciplines as social science and humanities. These people rarely agree on the time of day!