I guess it all depends how you define easy. The M1 from which the M14 evolved was not designed to take a scope. This deficiency was thought to have been corrected in the M14 with the groove and screw recess on the left side of the receiver. However no mount was developed. The first documented attempt to scope the M14 occurred in 1958 when LTC Frank Conway (Ret), while serving as an ordnance captain in the USAMTU mounted commercial Weaver K-6 scopes on two M14s by means of specially constructed bases. The front base was mounted on the barrel with the rear handguard clip removed and the hand guard was cut to fit. The rear base was affixed to the receiver in place of the rear sight. This required a high ring in front and a low ring in back. It took years to develop the mounts we have now and they still are very limited in their utility. The Smith mount and the copies of it require the weapon to be modified from it's original design to accept it. They are all prone to loosening up and need to be constantly checked for tightness in the field. You are limited in your selection of optics by what fits on the base that is over the receiver. If you make the base longer you are adding weight and complexity. It can be done, but it's not a simple thing.
Locating the safety inside the trigger guard might have been fine in the 1930s when the M1 was designed. But how we use weapons has changed substantially since then. The M14 is limited because it requires one to place his finger inside the trigger guard to move the safety to the off position.
That may be fine for you shooting on the range, but for tactical operations it's a big no go. Not many people are going to want you running around with a locked and loaded weapon and the safety off. Despite the line in the movie Blackhawk Down where the CAG operator tells the Ranger captain, "This is my safety" while pointing at his head while going through the chow line with a slung weapon, no military or police unit that I am aware of advocates safety off for tactical operations although I do know of a couple that are armed with MP5s that make entries with safeties off, but that is strictly due to the poor ergonomics of the MP5 platform. It's too easy for something to get caught in a trigger guard while you are all jocked up in body armor and other equipment and engaged in activities like moving through the woods, climbing in and out of windows, narrow doors, mouse holes and going hands on with a subject a suspect in a police tactical operation or a terrorist suspect in a military operation. What's a non issue on the range is a big issue in a tactical operation.
A complete history of the efforts to scope the M14 can be found starting on page 239 in The Complete Book of US Sniping by Peter R Senich, Collector Grade Publications 1988.
In fairness the FAL is as problematic to scope as the M14, requiring a new dust cover or a large machined mount to fit over the dust cover.
