The differences are really marginal between machine or hand padding if you use the machine very skillful, but still, the result of the handwork will have a nicer result. The bridle has a shortage (even when you use a lapel dart) to bring itself close to the body to prevent gaping. This means the lapel gets some length to the outside, in order to keep that in place you are actually doing a three dimensional hand padding. With machine padding you will loose that third dimension in Z coordinate, as the machine only does X and Y direction.
The problem is a psychological one. The owning of a machine is becoming a curse of a good tailor who understand this background because he use the machine to do a kind of incorrect, incomplete work for the gain of time. A real tailor loves is work and strives for artistic work like a spiritualist and scamping for the sake of time is a horror or betrayal of the tailors conscious. So the tailor, who uses the padding machine will mostly have a dirty look at his lapel work and rather closes his eyes and asking himself, why the heck I have bought a padding machine in order to don't like my work?
But there are tailors who have a certain love of their work regarding to be needy and little love to their work as they don't work spiritual, those are the ones who have left the street of being really artists. They have been giving in to the sorrows of their live in order to put food on the table, they have become slaves to cheap customers and have no other choice than to do so. If someone bought such a padding machine, he mostly becomes a slave to use it.
The tailor, I know in Germany, it took him at least 40 years to despise the existence of this machine in his shop and that is a long fight over the little Z-coordinate, he can grab over his fingers whilst padding or leave it alone by using the machine, but then having a dirty look all the time at his lapel, because a real tailor sees the little difference and that means he loves his work.