What I have found interesting as a recent convert is how people come in late for the liturgy. I do know that what others do is not my concern and that I should focus on my own behavior. I am not judging the other members of my parish, it is just something that I find very different from my Protestant upbringing.
Our liturgy starts at 10:30 a.m. and I am usually there by 10:15. when I enter the church there are about a dozen people already there. From the time the liturgy begins at 10:30 until the Great Entrance, the number of people increases to about 125-150. The vast majority arrive after the homily is given, or just before; in other words, after the service has been going on for about 30-45 minutes. Prior to that, the number in attendance only grows from the initial dozen to maybe 30-40. People trickle in throughout the service.
I realize the variables involved, such as traffic and the like, some however religiously arrive after the gospel reading or the homily, week after week. I often wonder if it is because they are not planning to commune or are mainly there for the luncheon that occurs afterwards. In my parish only about 8-10 people commune each week out of the 125 or so there. My priest encourages frequent communion, but told me that most of the parishioners come from a background where it was not common. A lady I know at the parish told me that when she was growing up back east, at the church she attended, most only took communion once a year.
I take communion primarily during the weekday feasts because only about 5-10 people show up. As a recent convert I feel uncomfortable communing on Sunday in front of long term parishioners that never go forward accept at Easter or some other time. ( I don't want to "rock the boat" or seem like an "uppity" convert). In the nearly one year that I have been attending I have seen people that are there every Sunday (and on time) who I have never seen commune.
As I stated, I am not criticizing my fellow parishioners, something that I would never have a right to do, I just find it interesting considering my prior religious background where everyone showed up on time if at all possible. People were embarrassed to enter the church late. Is this common in most Orthodox churches? Is it more common in some jurisdictions than in others, or common in the "old country"?
As an aside, the lady that I am a friend with says that coming in late was not the practice in the Orthodox church she grew up in back in Pennsylvania.
When you take into consideration the Orthros as well as the Liturgy it comes to a 3 hour service with no intermission. Once someone decides that they or their children are not able or willing to come at the start of the Orthros it becomes very easy to mentally make the decision to arrive at any hour.
Then you have the issue of why they are coming anyhow. Some are coming for the social aspect as you mentioned. Some for communion. Some to hear the gospel or sermon.
In my experience attendance increases or decreases based on participation. If the laity are singing hymns, prayers, creed, have some role in the service ie passing trays, distributing candles, welcoming parishioners, taking attendance for statistics or even just standing at a specified office they are much more likely to come on time to fulfill their obligation. Even an individual commitment to follow along in the service book makes a big difference.