Compare a case of meiotic drive where 70% of the pollen and 40% of the ovules carry the A allele independently, with a case of non independent assortment where an offspring gets an A allele from the pollen with probability 0.7 when the ovule provides an A and gets an A allele from the pollen with probability 0.3 when the ovule provides an a. The ovule provides A with probability 0.5.
One force that can alter the ratio of heterozygotes produced by a selfing heterozygote is meiotic drive, where one allele, say A, pushes its way into more than half of the gametes. Another possibility is that the alleles in surviving offspring are not independent. Compare the fraction of heterozygotes produced in the above case.