Washing clothing is dependent on a few different things:
- Time duration and harshness of mechanical washing action
- Water Temperature
- Water Volume
- Chemical Action
If you can imagine, a pie chart with all of these factors which come into play.
Since HE machines use less water and colder water temperatures, the other factors, such as chemical action and mechanical washing action must be increased to compensate to allow for the same amount of cleaning action.
I won't debate Non-HE vs HE washing here.
What I will say is that most front loading washing machines on the market are HE by default because they tend to use less water, soap and fabric softener than other types of machines.
I can't think of any front-loading machine that isn't HE, in all honesty.