Granted, this is personal experince, not factoids of a web page, but my grampa is a cattle dealer and I spent lots of days on farms besides ours.
“Milking machines often cause cuts and injuries that would not occur were a person to do the milking.”
Have never personally seen this, although it may happen on factory farms where cows don’t really get individual attention. In my experience, cows are most likely to injure their own teats - they step on their own when getting up or get stepped on out in the pasture. Almost as horrible is when cow A steps on the tail of cow B 
“In some cases, milking machines even give cows electric shocks due to stray voltage…”
True, but I don’t know that it’s caused exclusively by the milking machines. Every now and again a whole herd is electrocuted in their stanchions when a stray wire or stray voltage zaps the steel. On the other hand, every now and agin a whole herd is electrocuted because they took shelter underneath a single tree/grove of trees during a thunderstorm. Your call.
“Large dairy farms also have a detrimental effect on the surrounding environment…”
Oh, yeah, absolutely. It’s why I really hate factory farms of any sort, be it hogs or chickens or cows.
“Cows on today’s farms live only about four to five years…”
I think we keep them around for 7-10 years. Dad really doesn’t like to get rid of them when they stop producing, but after a certain point you put more money into feeding them then you get out of them in milk. Small farmers are on the margin already and don’t have the cash to run a retirement community. It sucks, but that’s life. Humans give their old people to nursing homes, dairymen give their old cows to Mickey D’s.
“…as opposed to the life expectancy of 20-25 years enjoyed by cows of an earlier era…”
What earlier era?
“Farmers also use an array of drugs, including bovine growth hormone (BGH); prostaglandin, which is used to bring a cow into heat whenever the farmer wants to have her inseminated…”
We don’t use this, and while I’ve been out of the farming loop for a while I don’t think many small farmers do.
“…tranquilizers…”
Damn, wish I had known about that one BEFORE I got kicked by those fresh heifers that had never been milked before 
“antibiotics”
Well, duh. If a cow gets sick or gets an infection, what do you want us to do? Let her die?
“Perhaps the greatest pain suffered by cows in the dairy industry is the repeated loss of their young. Female calves may join the ranks of the milk producers, but the males are generally taken from their mothers within 24 hours of birth…”
Ehhhhhh, well…All calves are taken from their mothers ASAP after birth. I suppose it might be a bad thing, but not nearly as bad as taking puppies or kittens from mama, and not nearly as noisy as taking a foal from its mare. Also, and this is just opinion, it seems that it would be safer for a calf to be separated from the herd and put in a pen with animals of its own size.