I think Joseph’s point is that on the shidduch itself it can be harder for the boy than for the girl. He has the stress of driving which is always much worse when there’s someone else in the car, particularly a shiduch. Since he arranged it he mentally takes achrayus for the success of the venue and that she should like it. And the worry that the condition of his car won’t put her off.
It is true the girl also has to worry about how she looks and dresses and what she says, however those are the very things which the whole purpose of the shidduch is to ascertain. If the boy only needed to worry about the main relevant points then it would be like with like. However I hope that the success of the shidduch doesn’t depend on how he drives on a shidduch, so this is secondary, and he has all these zeitige secondary daagos dumped on his head alone. How is a quieter boy supposed to juggle all these things while also maintaining scintillating conversation. A quieter girl doesn’t have to worry about any of these things while on the actual shidduch, and the things she worries about before the shidduch are things which are “the etzem zach”.