The problem you are seeing is because at least two of your domain values are so close that, compared to the range of values, they are on top of each other. So the minimum width between adjacent values is effectively 0. This causes the bar width to be reduced to the minimum of 1.
If you want to see all of your domain values spaced out equally as if they were discrete values, you could convert your datetime values into strings, or add hAxis: { type: 'category' } to your options. Here is a working version of your jsfiddle:
https://jsfiddle.net/11xztusu/9/