I have been working at garages almost since I first got into this server, and I have been owning one for over a year and a half. And although my garage isn't one of the most actives nor with the most mechanics (the first intention wasn't to make money out of it, but as a meeting spot for the car community where each driver could work on their cars for a low price), I have always seen a pattern whenever a car update came.
Normally, such update would bring, let's say, 10-15 cars. So every mechanic and garage owner know that during the next two to three days, the business will be booming. This has always been the case, before and after the first garage revamp (where the components were changed and the lease price got raised).
However, these past few days it's been different, I believe, because of different factors.
First, we have received over 60 cars in less than a week, making more people want their car(s) serviced and upgraded.
Second, there has been an important decrease in the number of truckers, specially knowing that the garages aren't the only ones that need components, but so do other kinds of businesses.
Third, there are less and less garages active. This might be caused by what other players mentioned earlier (components revamp leading to mechanics making less cash, players with play to win mentalities getting the leases over players invested in heavy roleplay). The problem is that because there are less garages, the people flood the ones remaining whenever they open. In my case, today, we only opened once (to do different cars for friends), and people passing by took the opportunity to get their car done, which we gladly did. In the end of the day, we didn't even need to post a single ad to get our components completely wiped out.
If we add all this up, we get to the situation we are today. A garage opens, they get wiped out, no one refills, and no one gets their cars upgraded/serviced.
P.S.: Even to do the maintenance on a car, we need components.
It would be funny to get to a stage where all the cars needed to be serviced, but none could. BMX life.