There is only one post with the tag 4g and one for lte. Seems most of the questions tagged with 3g was related to mobile data applications - probably it is appropriate to merge these tags into one, say [mobile-data] or [3g/4g/lte].
6It appears as though the post author is misusing the privilege to create a new tag...this is why we need to give that privilege only to more trusted users.– gparyaniJul 9, 2014 at 18:50
After looking at the tags 4g and lte, it seems there are no questions tagged with them, and so the tags will have been automatically deleted.
It may be a bit more of a problem with 3g because there are 145 questions so removing is not an option.
I think the best solution to this problem would be to merge them (like you said).
We will have to wait until a moderator or a high rep user can do this.