For energy tax, You don't get to see it on the top bar, you have to hover indiviual energy source to see the taxes in effect. e.g. click on a technician pop and hover over the "Produces: Energy XXX.XXX" on the right to see a complete breakdown of why this pop produce this much energy. You can also hover over your dyson sphere production hint to see it.
Regarding the influence, you should see a modifier "In federation: -2.00" or "In federation: -1.00" when hovering over your influence storage on the top bar. This is that tax the wiki is mentioning. It will be -1.00 instead of -2.00 if you have adopted diplomacy tradition tree, which is often the case because you need to pick a diplomacy tradition to form federation (you don't need that tradition to join an existing federation, but the sheer influence cost would urge you to adopt diplomacy tree ASAP).
