My sister was granted a 10-year long visa in 2007 when she was trying to go visit our uncle who lives in the US, we were told at the time that this is almost unheard of especially for children. How unusual is it really? We are all South Africans. She has to reapply for one now if she wants to go visit him again.
It shouldn't be all that unusual, especially for adults. US visas are typically issued on the basis of reciprocity, meaning that the US generally grants visas that last as long as a country grants visas to Americans (of course, Americans don't generally need a visa to visit South Africa for short tourist visits).
You can lookup the reciprocity schedule for South Africa on the US State Department website. It lists a 10-year multiple entry visa for B-1/B-2 visas (note that "fee: none" here simply means an additional visa fee; you still have to pay the normal application fee).
Consular officers are, per 9 FAM 403.9-4(B), "encouraged" to issue visas for the full duration listed in the reciprocity schedule, though they have the discretion to issue visas for a shorter period of time if they believe there's particular reason to do so:
b. (U) Posts Encouraged to Issue Full-Validity Visas: Posts are encouraged to issue full-validity visas. The routine issuance of limited validity visas runs contrary to that policy. Although 22 CFR 41.112(c) gives you the discretion to limit visa validity, this authority should be used very sparingly, preferably under the guidance of an experienced consular manager, in cases where the applicant’s current circumstances meet the requirements for visa issuance but may not continue to do so in the long term.
In short, a 10-year visa for South African citizens should generally be the norm, with some exceptions.
It seems very common. Maybe not for children but I always thought it was standard for B1/B2 visas. I personally qualify for the visa waiver programme but those of my friends who applied to visit the US got a 10-year visa on the first try, without any special request or evidence.
But Wikipedia indicates this actually depends on your country of origin, with 10 years being the default for most of South America, Europe and East Asia, and, indeed, South Africa. On the other hand, most of Africa falls into more restrictive categories, which might account for the perception that 10-year visas are rare.
depends on several factors... you normally get at the first time only a 2 years visa, then (if you use the visa) you can apply again and they will grant you another for 10 years....
I know people from south america who got a 1 year visa and never use it, after that getting a visa is hard (they will use that as argument to deny/refuse your application)
for adults is quite easier since the biometry remains almost the same.