
Gary L. answered 08/03/19
Patient and Understanding Tutor
I understand where this can seem confusing as certain languages will say things translating to "many thanks," "good mornings" and other hopes for a plural.
In English it is more common for these to instead be singular, like saying "Thanks" or "Good morning." So in the case of lots or a lot, lots is plural and would likely be found in other languages, but English would have it as "Thanks a lot" to make it singular. At the same time, telling someone "Thanks lots" can sometimes be seen positively if you are thanking someone for one prior action and future actions. (I would recommend keeping this use of the phrase to speaking in person rather than formal writing)