Non-Mega Charizard does not fit OU standards, nor does Typhlosion for that matter.
People don't know that the opposing Charizard is not a mega, which adds to a lot of mind games. In total that means that there are three types of Charizards that are possibly on the opponent's team, and most expect one of the either Mega formes.
And while normal Charizard is nearly non-existant in the OU tier, it's mega, Mega Charizard Y, is one of the most popular and powerful megas in the whole metagame, that gets serious firepower in the sun, along with near perfect coverage. This more than makes up for the Eruptions Typhlosion has. Also it can set it's own weather without using up a turn.
Most people expect this and bring along counters for this, while the actual mega is hiding in the rear, waiting for the chance to ruin the opponent. Imagine if you actually think that it's a Megazard Y the opponent has, and he decides to surprise you with his Mega Medicham.
People also predict Mega Charizard X, which is arguably one of the besst Dragon Dancers available in the tier, as it is immune to burn.
Hope I helped!